العربية
中国
Français
Deutsch
Ελληνική
हिन्दी
Italiano
日本語
Português
Русский
EspañolINTERSTATE HIGHWAY SYSTEM
(Redirected from Interstate highway)
The 'Dwight D. Eisenhower National System of Interstate and Defense Highways', commonly called the 'Interstate Highway System', is a network of highways (also called freeways or expressways) in the United States that is named for the president who was in office when the system was created. The Interstate Highway System is a separate system within the larger National Highway System. The entire system, as of 2004, had a total length of 46,837 miles (75,376 km) [1].
While Interstate Highways usually receive substantial federal funding and comply with federal standards, they are owned, built, and operated by the states or toll authorities. The original Woodrow Wilson Bridge, part of Interstate 95 and Interstate 495, was maintained by the federal government; its new span is now jointly owned and maintained by the State of Maryland and the Commonwealth of Virginia .[1]
The system serves nearly all major U.S. cities. Unlike counterparts in most other industrialized countries, many Interstates pass through downtown areas. This has helped to facilitate the emergence of automobile-oriented postwar suburban development patterns, a phenomenon also known as urban sprawl.
The system is prominent in American daily life. The distribution of virtually all goods and services involves Interstate Highways at some point. Residents of American cities commonly use urban Interstates to travel to their places of work. The vast majority of long-distance travel, whether for vacation or business, uses the national road network;[2] of these trips, about one-third (by the total number of miles driven in the country in 2003) utilize the Interstate system.[3]
The interstate system was authorized by the Federal-Aid Highway Act of 1956, popularly known as the National Interstate and Defense Highways Act of 1956. It had been lobbied for by major U.S. automobile manufacturers and championed by President Dwight D. Eisenhower- who was influenced by both his experiences as a young soldier crossing the country in 1919 following the route of the Lincoln Highway and his appreciation of the German autobahn network - as a necessary component of a national defense system. [4] It would be able to provide key ground transport of military supplies and troop deployments.
Initial federal planning for a nationwide highway system began in 1921 when the Bureau of Public Roads asked the Army to provide it with a list of roads it considered necessary for national defense, resulting in the Pershing Map. Later that decade, highways such as the New York parkway system had been built as part of local or state highway systems. As automotive traffic increased, planners saw a need for such an interconnected national system to supplement the existing, largely non-freeway, United States Numbered Highway system. By the late 1930s, planning had expanded to a system of new superhighways. The publication ''General location of national system of interstate highways'' maps out what became the interstate system, and is informally known as the ''Yellow Book''. [2].
Although construction on the Interstate Highway system continues, the removal of the last traffic signal on Interstate 90 in Wallace, Idaho, on September 15, 1991 is often cited as the completion of the Interstate System. The initial cost estimate for the system was $25 billion over twelve years; it ended up costing $114 billion (adjusted for inflation, $425 billion in 2006 dollars[5] and taking 35 years to complete [3].
However, due to the cancellation of the Somerset Freeway, Interstate 95 is discontinuous in New Jersey. When the Pennsylvania Turnpike/Interstate 95 Interchange Project concludes around 2009, the last section of the basic original plan will be completed.
Missouri and Kansas have laid claims that I-70 in those states was the first interstate (Missouri also says I-44 is one of the first). The first three contracts under the new program were signed in Missouri on August 2, 1956. Kansas claims that it was the first to start paving after the act and that the Kansas portion of I-70 was the first complete section. However, construction and planning on those roads had been underway before the highway act. The Pennsylvania Turnpike, which opened on October 1, 1940, claims to be the first limited-access, divided highway in the country. [4]
Main articles: Interstate Highway standards
The American Association of State Highway and Transportation Officials (AASHTO) has defined a set of standards that all new Interstates must meet unless a waiver from the Federal Highway Administration (FHWA) is obtained. These standards have become more strict over the years. One almost absolute standard is the controlled access nature of the roads. With few exceptions, traffic lights (and cross traffic in general) are limited to toll booths and ramp meters (metered flow control for lane merging during rush hour).
Interstate Highways often have the highest speed limits in a given area. Speed limits are determined by individual states. Rural limits generally range from 65 to 80 mph (104.6 to 128.7 km/h) typically with the lower limits in the more populated northeastern states and the higher speeds in the western states, with the exception of Oregon's state speed limit ceiling of 65 mph. Urban interstate speed limits are generally 50 to 65 mph (80.5 to 104.6 km/h) across the country.
In addition to being designed to support automobile and heavy truck traffic, interstate highways are also designed for use in military and civil defense operations within the United States, particularly troop movements.
One potential civil defense use of the Interstate Highway System is for the emergency evacuation of cities in the event of a potential nuclear war. The Interstate Highway System has been used to facilitate evacuations in the face of hurricanes and other natural disasters.
An option for maximizing traffic throughput on a highway is to reverse the flow of traffic on one side of a divider so that all lanes become outbound lanes. This procedure, known as contraflow, was first employed in the 1998 evacuation of New Orleans, Louisiana in preparation for Hurricane Georges. Contraflow was also employed in the 2004 evacuation of the Tampa, Florida, area ahead of Hurricane Charley and again 2005 during the evacuations of New Orleans, Louisiana, and Houston, Texas, prior to hurricanes Katrina and Rita, respectively.
A widespread urban legend states that one out of every five miles of the Interstate Highway System must be built straight and flat so as to be usable by aircraft during times of war. Contrary to popular lore, Interstate highways are not designed to serve as airstrips. [6][7]
While the name implies that Interstate highways cross state lines, many do not (For details, see List of intrastate Interstates). Rather, they are ''funded'' federally with money shared ''among the states''. There are interstate highways in Hawaii, funded in the same way as in the other states, but entirely within the populous island of Oahu. They have the designation of H-X and connect military bases. Similarly, both Alaska and Puerto Rico have public roads that receive funding from the Interstate program, though these routes are not signed as Interstate Highways except "on paper". These roads are neither planned for nor currently built to Interstate Highway standards.
The numbering system can be summarized in these general rules. One- and two-digit highways are national routes:
★ 'Odd numbered' routes run north-south, and higher numbers are farther east.[8]
:'I-5' runs up and down the West Coast, with 'I-95' on the East Coast.
★ 'Even numbered' routes run east-west, and higher numbers are farther north.
:'I-10' runs along the Southern states, and 'I-90' runs near the US-Canada border.
Three-digit highways, or Auxiliary Interstate Highways, run only within a single city.
★ An 'odd first digit' signifies a spur route, which may begin at a large highway and terminate at a city center.
:'I-110' travels into downtown Los Angeles.
★ An 'even first digit' signifies a loop route around a city or a bypass through a city.
:'I-215' travels the perimeter of Salt Lake City.
:'I-895' serves as a bypass of downtown Baltimore.
★ The last two digits signify the highway's origin.
:'I-215' eventually returns to I-15, a primary interstate highway.
:'I-185' in Georgia leaves I-85 to go into Columbus.
★ Sometimes, a three-digit highway branches off another three-digit highway; this is called a tertiary spur route of a two-digit highway. Tertiary spurs do not meet their parent highways, but are associated with them via the three-digit highways they do meet.
:'I-370' in Maryland branches off I-270, and is thus a tertiary spur of I-70.
Interstate highways are typically known as 'Interstate XX' or 'I-XX', where "XX" is the one- or two-digit route number; sometimes 'Interstate Highway XX' ('IH XX') or 'Interstate Route XX' ('IR XX') is used. In some areas, the more generic 'Route XX' or 'Highway XX' is used, or in the case of southern California, Nevada, and New York, 'The XX'.
The numbering scheme for the Interstate Highway System (as well as the U.S. Highway System) was developed in 1957 by the American Association of State Highway and Transportation Officials (AASHTO) and is still coordinated by them, though their authority is occasionally trumped by a number written into Federal law. Within the continental United States, primary Interstates (also called main line Interstates or two-digit Interstates) are given one- or two-digit route numbers. Most Interstates have two digits; there are only three one-digit Interstates in the system: I-4, I-5 and I-8. Within this category, east-west highways are assigned even numbers, and north-south highways are assigned odd numbers. Odd route numbers increase from west to east, and even numbered routes increase from south to north, though there are exceptions to both principles in several locations. Numbers divisible by 5 are intended to be major among the primary routes, carrying traffic long distances. For example, I-5 runs from Canada to Mexico along the west coast (the only interstate to do so) while I-95 runs from Miami north to Canada along the east coast. In addition, I-10 runs from Santa Monica, California, to Jacksonville, Florida while I-90 runs from Seattle, to Boston. However, not all primary routes divisible by 5 traverse long distances. I-45 runs from Galveston, Texas, north to Dallas, a distance of only 284 miles (457 km). It is the only primary route divisible by 5 that does not cross state lines. See List of intrastate Interstate Highways for other primary routes that do not cross state lines.
I-50 and I-60 do not exist (and there are no even-numbered Interstates from 46 to 62), mainly because they would most likely have passed through the same states that already have US 50 and US 60. AASHTO rules discourage Interstate and US Highways having the same number within the same state, although I-24 and US 24 exist at opposite ends of Illinois. Some planned Interstates do not follow this guideline — I-69 will intersect US 69 in Lufkin, Texas[9], I-74 will overlap US 74 in North Carolina, and I-41 will do the same with US 41 in Wisconsin.
Several two-digit numbers are shared between two roads at opposite ends of the country, namely I-76, I-84, I-86 and I-88. Some of these were the result of a change in the numbering system in the 1970s; previously letter-suffixed numbers were used for long spurs off primary routes; for example, western I-84 was I-80N, as it went north from I-80. In the 1970s, AASHTO decided to eliminate these; some became additional two-digit routes, while others became three-digit routes (see below). Only two pairs of these exist; I-35 splits into I-35W and I-35E through both the Dallas-Fort Worth and the Minneapolis-St. Paul areas.
For the sake of efficiency, some Interstates double up for short or sometimes long distances. This is usually referred to as a ''concurrency'' or ''overlap''. One example is where I-75 and I-85 combine just below downtown Atlanta to form the Downtown Connector, a major thoroughfare through the city. Another example is the merging and diverging of Interstates 90 and 94, which double and then separate several times across the upper Midwest and Great Plains. I-90 and I-94 even join with I-39 from Madison to Portage, Wisconsin, creating the longest triple concurrence in the Interstate system. Interstates 90 and 80 are concurrent for almost 280 miles in Indiana and Ohio. A recent addition is the I-73/I-74 concurrency, which runs along U.S. Route 220 from Asheboro to Rockingham, North Carolina. I-73 will also share routes with I-40 and I-85 on the Greensboro Urban Loop, a new bypass route around Greensboro, North Carolina. Strict adherence to the directional nature of the system results in some amusing oddities. For a nine-mile (14 km) stretch east of Wytheville, Virginia, the driver can be traveling on both I-81 ''North'' and I-77 ''South'' at the same time (and vice versa) (see also Wrong-way concurrency).
Auxiliary Interstate Highways are given three-digit route numbers, which consist of a single digit prefixed to the two-digit number of a primary Interstate highway, to designate spur or loop routes branching from either the primary route or one of its other auxiliary routes. A spur route is one that deviates from its parent and does not end at another Interstate; it is given an odd first digit. A loop route is one that returns to its parent; it is given an even first digit. The number given to the first digit of a route that branches from the parent to end at another Interstate depends on the state; some consider these routes spurs and assign odd first digits, while others consider them loop connectors giving them even first digits.
When letter-suffixed two-digit Interstates (see above) were abundant, their auxiliary routes were given a number without a letter suffix (with the exception of I-180N in Boise, Idaho, which is now Interstate 184).
Due to the large number of these routes, auxiliary route (aka "spur route") numbers may be repeated in different states along the mainline; but no two three-digit Interstates in the same state can share a number. For instance, I-90 in New York alone has a full set of three-digit Interstates - I-190, I-290, I-390, I-490, I-590, I-690, I-790, I-890 and I-990.
Closed loops usually retain a single designation for the entire route, even when they enter other states. For example, Cincinnati, like many other cities, features a large loop around the city that intersects with the primary routes I-71, I-74, and I-75 and travels through Ohio, Kentucky, and Indiana. The entire 84 mile (135 km) loop is labeled I-275. (It is also the only three-digit interstate to ever go through three states.)
The loop highway around Washington, D.C., known as the Capital Beltway, carries both I-95 and I-495. Originally, the loop carried only I-495, in anticipation of I-95 being routed through Washington, but in 1977, I-95 was rerouted on the eastern half of the loop due to the cancellation of the segment that would have connected downtown Washington to College Park, Maryland, while I-495 remained on the western half. I-495 was added back to the eastern half of the loop in 1989, creating a rare concurrency of primary and auxiliary routes.
Unlike primary Interstates, three-digit Interstates are signed either east-west or north-south depending on the general orientation of the route, without any regard to the route number. For some looped Interstate routes, Inner and Outer banners are used as a directional labeling system as opposed to compass directions.
Of course, there are exceptions to these guidelines:
★ A contiguous loop surrounds the entire Minneapolis-St. Paul Metro area. I-94 intersects the loop in two spots and runs directly through it separating it into southern and northern halves; the southern half of it is labeled I-494 while the northern half of it is labeled I-694. The northern half rejoins I-94 approximately five miles before the southern half does; this stretch is signed I-94/I-694.
★ I-270 and I-255 form a beltway around the greater St. Louis area. On its southwest corner, I-270 becomes I-255 as it crosses I-55 counter-clockwise only to terminate back at I-270 in the northeast. In the early 1980s, local residents stopped a plan to designate the entire closed loop as I-270 and renumber the stub of I-270 from Glen Carbon to Edwardsville to I-870.
★ New York City has numerous spur routes off from I-78 and I-95, but none of I-78's spur routes actually intersect with I-78.
★ An auxiliary route numbered I-238 connects San Leandro and Castro Valley, California, yet there is no I-38. Instead, I-238 carries the designation of the portion of State Route 238 that the Interstate designation replaced. I-238's parent route is I-80, and at the time of I-238's designation, all child routes of I-80 (I-180 through I-980) were already designated in California.
A major exception to the overall numbering system is Interstate 99 in Pennsylvania, which was written into law as I-99 by Pennsylvania Congressman Bud Shuster; I-99 (which is also U.S. Route 220) is west of several Interstates that are numerically less than 99, but 99 was the nearest odd 2-digit number available for the interstate.
A less-notable exception is I-82, which lies fully north of I-84; this is a relic from I-84 previously having the designation of I-80N.
Some Proposed Interstate Highways have been given similarly non-conforming designations by their legislative proponents. For example, backers of the proposed Third Infantry Division Highway, a route in Georgia and Tennessee, have suggested it be named Interstate 3, in honor of the U.S. 3rd Infantry Division.
The following two-digit Interstates change signed direction from their normal (even=east-west, odd=north-south) direction:
★ I-69 east of Lansing, Michigan
★ I-76 in Nebraska
The I-69 segment is an extension of its original route; I-76 only runs for two miles (3 km) in Nebraska before ending at I-80.
Two-digit Interstates in Hawaii, as well as the "paper" Interstates of Alaska and Puerto Rico, are numbered sequentially in order of funding, without regard to the rules on odd and even numbers.
Business Loop and Business Spur Interstates are not subject to any of the Interstate Highway standards. Their designation is simple - a Business Loop heads into a downtown area from its parent and returns to its parent; a Business Spur ends downtown, occasionally continuing from the end of the main Interstate. Business routes can split from either two- or three-digit Interstates, and can be repeated within a state. In a few cases, where an Interstate has been realigned, the old road has been designated a Business Loop because it is not up to standards.
About 56%[10] of the construction and maintenance costs are funded through user fees, primarily gasoline taxes, collected by states and the federal government, and tolls collected on toll roads and bridges. The rest of the costs are borne by the federal budget. In the eastern United States, large sections of some Interstate Highways planned or built prior to 1956 are operated as toll roads. The taxes dedicated to the construction and maintenance of highways are sometimes criticized as a direct subsidy from the government to promote and maintain auto-oriented development.
As American suburbs push ever outward, the costs incurred in maintaining freeway infrastructure have grown, leaving little in the way of funds for new interstate construction [11]. This has led to the proliferation of toll roads (turnpikes) as the new method of building limited-access highways in suburban areas. Also, some interstates are being privately maintained (e.g., VMS maintains I-35 in Texas) in order to cut rising costs of maintenance and allow state departments of transportation to focus on serving the fastest growing regions in their respective states. The future of the interstate system as we know it is in question. It is possible that parts of the system will have to be tolled in the future to meet maintenance and expansion demands, as has been done with adding toll HOV/HOT lanes in certain cities like San Diego, Salt Lake City, Minneapolis, Houston, Dallas, Atlanta and Washington, D.C.
The dominant role of the federal government in road finance has enabled it to achieve legislative goals that fall outside its power to regulate interstate commerce as enumerated in the federal Constitution. By threatening to withhold highway funds, the federal government has been able to stimulate state legislatures to pass a variety of laws. Although some object on the ground that this infringes on states' rights, the Supreme Court has upheld the practice as a permissible use of the Constitution's Commerce Clause.
The first major example was the introduction of the 55 mph (90 km/h) national speed limit in 1974. While its purpose was to save fuel in the wake of the 1973 energy crisis, federal speed controls stayed in effect for 21 years. The initial acceptance of the national speed limit emboldened various presidents and Congresses to enact additional pieces of legislation, some of which have little to do with highways or transportation. Examples include:
★ Increasing the legal drinking age to 21.[12]
★ Megan's Law legislation, requiring states to disclose identities of sex offenders.
★ Lowering the legal intoxication level to 0.08%.
★ Requiring the use of carpool (HOV) lanes.
States must also meet minimum enforcement standards for all federally-mandated legislation (for example, minimum penalties for violation of these laws and a minimum number of per capita underage drinking convictions or a compelling explanation regarding why this number is not met). This has proved to be controversial. Supporters hold that it is a way to provide an impetus to states to pass uniform legislation. Critics maintain that using highway dollars in this fashion upsets the balance between federal and states rights in favor of the federal government, and effectively holds funds as ransom in order to coerce state governments into passing laws that would not have otherwise been introduced. Some have even argued that the current arrangement is unconstitutional. Law enforcement agencies in some states argue that efforts to meet quotas for underage drinking convictions have distracted them from other matters and strained relations with those under 21. Any state that was to lose federal highway funding would quickly face deteriorating infrastructure, fiscal impoverishment, or both.
Of course, a state that lost federal highway funding ''could'' theoretically threaten to stop maintaining its highways, if that were politically palatable to its residents.
A few Interstates are maintained by local authorities:
★ Baltimore, Maryland: Interstate 70 and Interstate 83 in the city limits[13]
★ New York City: Small portions of Interstate 278[14]
★ Washington, D.C.: As the city and District are identical, the District maintains the portions of Interstate 66, Interstate 295, Interstate 395 and Interstate 695 inside the city.
In addition to Interstate highways financed with federal funds (Chargeable Interstate routes), federal laws allow other highways to be signed as Interstates, if they meet the Interstate Highway standards and are logical additions or connections to the System.
Called Non-Chargeable Interstate routes, these additions fall under two categories:
# Routes that already meet Interstate standards. These may immediately be signed as Interstates once their proposed number is approved, or may be retained with a non-Interstate designation.
# Routes not yet upgraded to Interstate standards. These cannot be signed as Interstates until they have been fully upgraded.
The majority of Interstates have exit numbers. All traffic signs and lane markings on the Interstates are supposed to be designed in compliance with the Manual on Uniform Traffic Control Devices (MUTCD). However, there are many local and regional variations in signage.
For many years, California was the only state that did not use an exit numbering system. It was granted an exemption in the 1950s due to having an already largely completed and signed highway system; at the time, placing exit number signage on the signs across the state was deemed too expensive. Since 2002, however, California has begun to incorporate exit numbers on all of its freeways - interstate, U.S., and state routes alike. To mitigate costs, a common occurrence is for Caltrans to install exit number signage only when a freeway or interchange is built, reconstructed, retrofitted, or repaired. The majority of the exits along Interstates 5, 10, and 80 now have exit number signage, particularly in rural areas.
In most states, the exit numbers correspond to the mileage markers on the Interstates (with an exception being I-19 in Arizona, whose length is measured in kilometers instead of miles). On even-numbered Interstates, mileage count increases to the east and decreases to the west (except on the I-90 portion of the New York State Thruway, I-90 between Chicago and Rockford, IL, the I-190 spur into O'Hare International Airport in Chicago, and the portion of I-76 in New Jersey, all of which count up going west); and on odd-numbered Interstates, mileage count increases to the north and decreases to the south and the exit numbers increase and decrease accordingly.
Many northeastern states label exit numbers sequentially, regardless of how many miles have passed between exits. States in which Interstate exits are still numbered sequentially are: Connecticut, Delaware, Massachusetts, New Hampshire, New York, Rhode Island and Vermont. Maine, Pennsylvania, Virginia, Georgia, and Florida followed this system for a number of years, but recently converted to having the exit numbers correspond to mileage markers. The Pennsylvania Turnpike uses both the mile marker number and the sequential number. The mile marker number is used for signage, while the sequential number is used for numbering interchanges internally. The New Jersey Turnpike also has sequential numbering, but other interstates within New Jersey generally use mile markers.
Interstate Highways are signed by a number on a trademarked red, white and blue sign as shown to the right. In the original design, the state was listed above the highway number, but in many states, this area is now left blank. The sign itself usually measures 36 inches (91 cm) high , and is 36 inches wide for two-digit interstates or 45 inches (114 cm) for three-digit interstates.
Business Loop and Business Spur Interstates use a special shield where the red and blue are replaced with green; the word BUSINESS appears instead of INTERSTATE, and the word SPUR or LOOP usually appears above the number.
Over time the design of the interstate shield has changed. In 1958, when the interstate shield was introduced, the shield color was actually a dark navy blue and only 17 inches wide. The MUTCD standards made few revisions to the shield in the 1961, 1972, 1988, and 2000 editions. However, by the 1980s, many Northeastern states began to omit the name of the state from the shield and switch to general shields. Also, the color of some shields has become a brighter shade of blue. By 2000, the shield size nearly doubled, some interstate shields reaching 36 inches in diameter.
Many states have few or no shields with the name of the state, such as Washington, Oregon, Idaho, Ohio, Nevada, Utah, Indiana and Illinois. Many times, older state-name shields can only be found at areas isolated from the highway network, such as rural municipalities or in urban areas away from the actual interstate (e.g. the Interstate 4 state-name shield remaining in Orlando). States like New York, Delaware, New Hampshire, Pennsylvania, have almost no state-name shields remaining.
Many states are in the process of switching from state-named shields to neutral shields, resulting in a mix of some state shields and the more recent general shields. Numerous southeastern states have been neutering the shields ever since the mid to late 1990s, and some began in 2000. Louisiana began neutering the shields ever since the 1990s. In Alabama the recently-made shields are neutral shields. One can still find many state shields in some cities, but some highways with newer signage have neutral shields. TxDOT started neutering the shields in the early 2000s. In northeastern Texas most of the shields are neutral. In southeastern Texas, one might still see many state shields. Interstate 635 state shields might still be found, but most 3-digit interstate shields lack state names.
States such as California, Arizona, New Mexico, Oklahoma, Missouri, and even Iowa and Maryland still use shields with the state name. In California, many recently placed interstate shields still use the state name (mostly in the metropolitan cities, especially the 3-digit interstate highways). In Kansas, KDOT still uses the state-name shields while the KTA does not. You still find almost all the interstates in Metropolitan Oklahoma City, Kansas City and Metropolitan St. Louis still use interstate shields with state name printed, even those new ones. In Iowa and Maryland there are still many shields with the state name.
The most heavily traveled area of the Interstate Highway system is the 405 Freeway in Seal Beach, California, with a 2002 estimate of 377,000 vehicles a day. The least traveled section is Interstate 95 just north of Houlton, Maine (near the Canadian border), with 1,880 vehicles a day (2001 estimate).
The most extreme directional points of the Interstate Highway system are:
★ Northernmost-the northern termini of Interstates 5, 15, and 29, crossing the Canadian border at the 49th parallel near, respectively, Blaine, Washington, Sweetgrass, Montana, and Pembina, North Dakota.
★ Southernmost-a bend on Interstate H-1 in the Kaimuki section of Honolulu, Hawaii, less than half a mile (0.8 km) before its eastern terminus (lat. 21.3 deg. N.). The southernmost point in the 48 contiguous states is the southern terminus of Interstate 95 in Miami, Florida (lat. 25.8 deg. N.).
★ Easternmost-the northern terminus of Interstate 95 near Houlton, Maine, at the border of New Brunswick in Canada (long. 67.8 deg. W.).
★ Westernmost-the western terminus of Interstate H-1 in Kapolei, Hawaii (long. 158.06 deg. W.). The westernmost point in the contiguous states is a curve on Interstate 5 near Wolf Creek, Oregon (long. 123.23 deg. W.).
The highest point on the Interstate Highway System is at the Eisenhower Tunnel on Interstate 70 in the Rocky Mountains of Colorado, at the Continental Divide (elev. 11,158 feet (3401 m)). The lowest point is on Interstate 8 at the New River near Seeley, California (elev. -52 feet (-16 m)).
The longest Interstate highway is Interstate 90, which runs 3099 miles (4 987 km) between Boston, Massachusetts and Seattle, Washington. The longest north-south Interstate highway is generally cited as Interstate 95; when completed, it will run 1927 mi (3 101 km) between Miami, Florida and the Canadian border (there is a gap in New Jersey). The shortest Interstate is Interstate 878, a 0.7-mile (1.1 km) portion of New York State Route 878 adjacent to John F. Kennedy International Airport in Queens, New York. However, it is not officially signed. The shortest signed Interstate is Interstate 375 in downtown Detroit, Michigan, at 1.06 miles (1.71 km).
John Steinbeck, in his travelogue ''Travels With Charley'', claimed "When we get these thruways across the whole country, as we will and must, it will be possible to drive from New York to California without seeing a single thing." Charles Kuralt echoed this statement in his biography ''A Life on the Road'': "The interstate highway system is a wonderful thing. It makes it possible to go from coast to coast without seeing anything or meeting anybody. If the United States interests you, stay off the interstates." These quotes refer to the tendency of Interstate highways to emphasize more rapid, uninterrupted transportation than other road networks. This could be contrasted to the sometimes-romanticized perception of state and county routes, often two-lane highways, that may offer more chances to stop at local small businesses or see true rural America.
1. Attachment V, Ownership and Maintenance Agreement for the Wilson Bridge, Woodrow Wilson Bridge Initial Financial Plan
2. Table 1-36: Long-Distance Travel in the United States by Selected Trip Characteristics
3. Annual Vehicle Distance Traveled in Miles and Related Data
4.
5. Traveling interstates is our sixth freedom Al Neuharth
6. http://www.snopes.com/autos/law/airstrip.asp
7. ONE MILE IN FIVE: Debunking the Myth
8. ''The Dwight D. Eisenhower National System of Interstate and Defense Highways, Route Log and Finder List'', FHWA, March 2001
9. Interactive map
10. http://www.fhwa.dot.gov/policy/ohim/hs03/htm/hf10.htm 2003 FHWA summary
11. Field, David. "On 40th birthday, interstates face expensive midlife crisis." ''Insight on the News'', 29 July 1996, 40-42.
12. [South Dakota v. Dole]
13.
14. New York State Department of Transportation - Region 11 (New York City) Built and Unbuilt Arterial System
★ Contraflow
★ Gas tax
★ Highway patrol
★ Non-motorized vehicle access on freeways
★ List of roads and highways
★ Mile-log
★ Parkway
★ List of major freeway systems
★ Interstate Highway System chronology
★ Adopt a Highway
★ Interstate-Guide.com@Interstate shield galleries
★ Interstate Highway information
★ FHWA Route Log and Finder List
★ FHWA Turner-Fairbank Highway Research Center - Analysis and History of Interstate Highway System
★ History of urban interstates - Norton, "Fighting Traffic: U.S. Transportation Policy and Urban Congestion, 1955-1970"
★ 3-digit Interstate Highways
★ Pictures of all Interstates
★ One of 100 milestone documents of American history
★ Federal Highway Administration's article on the act
★ ''Fortune'' magazine on history of the Interstate Highway System
★ Tony Graham's Exit List Collection A compilation of all Interstate exit lists available online
★ Another great Interstate Page, with facts on all 2-digit Interstates and links to their exit lists
★ Highway Heaven Contains exit lists for most Interstate highways
★ RoadGeek - A complete set of TrueType fonts for simulating Interstate and other highway signage
★ 2006: 50th Anniversary of the Interstate Highway System Celebration - from the American Road & Transportation Builders Association
★ Interstate50th.org - A website that celebrates the system's golden anniversary, filled with facts and other interesting information about the highways, such as where the first miles of Interstate were built
Interstate Highways in the 48 contiguous states. Purple routes are currently built and open freeways, blue are currently open spur routes, and green indicates proposed routes, future roads, or those currently under construction.
A rural stretch of Interstate 5 in California, with two lanes in each direction separated by a large grassy median, and with cross-traffic limited to overpasses and underpasses.
The 'Dwight D. Eisenhower National System of Interstate and Defense Highways', commonly called the 'Interstate Highway System', is a network of highways (also called freeways or expressways) in the United States that is named for the president who was in office when the system was created. The Interstate Highway System is a separate system within the larger National Highway System. The entire system, as of 2004, had a total length of 46,837 miles (75,376 km) [1].
While Interstate Highways usually receive substantial federal funding and comply with federal standards, they are owned, built, and operated by the states or toll authorities. The original Woodrow Wilson Bridge, part of Interstate 95 and Interstate 495, was maintained by the federal government; its new span is now jointly owned and maintained by the State of Maryland and the Commonwealth of Virginia .[1]
The system serves nearly all major U.S. cities. Unlike counterparts in most other industrialized countries, many Interstates pass through downtown areas. This has helped to facilitate the emergence of automobile-oriented postwar suburban development patterns, a phenomenon also known as urban sprawl.
The system is prominent in American daily life. The distribution of virtually all goods and services involves Interstate Highways at some point. Residents of American cities commonly use urban Interstates to travel to their places of work. The vast majority of long-distance travel, whether for vacation or business, uses the national road network;[2] of these trips, about one-third (by the total number of miles driven in the country in 2003) utilize the Interstate system.[3]
History
Commemorative sign introduced in 1993. Though the system was established during Dwight D. Eisenhower's presidency, the five stars commemorate his rank as General of the Army during World War II.
The interstate system was authorized by the Federal-Aid Highway Act of 1956, popularly known as the National Interstate and Defense Highways Act of 1956. It had been lobbied for by major U.S. automobile manufacturers and championed by President Dwight D. Eisenhower- who was influenced by both his experiences as a young soldier crossing the country in 1919 following the route of the Lincoln Highway and his appreciation of the German autobahn network - as a necessary component of a national defense system. [4] It would be able to provide key ground transport of military supplies and troop deployments.
Initial federal planning for a nationwide highway system began in 1921 when the Bureau of Public Roads asked the Army to provide it with a list of roads it considered necessary for national defense, resulting in the Pershing Map. Later that decade, highways such as the New York parkway system had been built as part of local or state highway systems. As automotive traffic increased, planners saw a need for such an interconnected national system to supplement the existing, largely non-freeway, United States Numbered Highway system. By the late 1930s, planning had expanded to a system of new superhighways. The publication ''General location of national system of interstate highways'' maps out what became the interstate system, and is informally known as the ''Yellow Book''. [2].
Although construction on the Interstate Highway system continues, the removal of the last traffic signal on Interstate 90 in Wallace, Idaho, on September 15, 1991 is often cited as the completion of the Interstate System. The initial cost estimate for the system was $25 billion over twelve years; it ended up costing $114 billion (adjusted for inflation, $425 billion in 2006 dollars[5] and taking 35 years to complete [3].
However, due to the cancellation of the Somerset Freeway, Interstate 95 is discontinuous in New Jersey. When the Pennsylvania Turnpike/Interstate 95 Interchange Project concludes around 2009, the last section of the basic original plan will be completed.
Missouri and Kansas have laid claims that I-70 in those states was the first interstate (Missouri also says I-44 is one of the first). The first three contracts under the new program were signed in Missouri on August 2, 1956. Kansas claims that it was the first to start paving after the act and that the Kansas portion of I-70 was the first complete section. However, construction and planning on those roads had been underway before the highway act. The Pennsylvania Turnpike, which opened on October 1, 1940, claims to be the first limited-access, divided highway in the country. [4]
Standards
Main articles: Interstate Highway standards
The American Association of State Highway and Transportation Officials (AASHTO) has defined a set of standards that all new Interstates must meet unless a waiver from the Federal Highway Administration (FHWA) is obtained. These standards have become more strict over the years. One almost absolute standard is the controlled access nature of the roads. With few exceptions, traffic lights (and cross traffic in general) are limited to toll booths and ramp meters (metered flow control for lane merging during rush hour).
Speed limits
Interstate Highways often have the highest speed limits in a given area. Speed limits are determined by individual states. Rural limits generally range from 65 to 80 mph (104.6 to 128.7 km/h) typically with the lower limits in the more populated northeastern states and the higher speeds in the western states, with the exception of Oregon's state speed limit ceiling of 65 mph. Urban interstate speed limits are generally 50 to 65 mph (80.5 to 104.6 km/h) across the country.
Dual-purpose design
In addition to being designed to support automobile and heavy truck traffic, interstate highways are also designed for use in military and civil defense operations within the United States, particularly troop movements.
One potential civil defense use of the Interstate Highway System is for the emergency evacuation of cities in the event of a potential nuclear war. The Interstate Highway System has been used to facilitate evacuations in the face of hurricanes and other natural disasters.
An option for maximizing traffic throughput on a highway is to reverse the flow of traffic on one side of a divider so that all lanes become outbound lanes. This procedure, known as contraflow, was first employed in the 1998 evacuation of New Orleans, Louisiana in preparation for Hurricane Georges. Contraflow was also employed in the 2004 evacuation of the Tampa, Florida, area ahead of Hurricane Charley and again 2005 during the evacuations of New Orleans, Louisiana, and Houston, Texas, prior to hurricanes Katrina and Rita, respectively.
A widespread urban legend states that one out of every five miles of the Interstate Highway System must be built straight and flat so as to be usable by aircraft during times of war. Contrary to popular lore, Interstate highways are not designed to serve as airstrips. [6][7]
Terminology
While the name implies that Interstate highways cross state lines, many do not (For details, see List of intrastate Interstates). Rather, they are ''funded'' federally with money shared ''among the states''. There are interstate highways in Hawaii, funded in the same way as in the other states, but entirely within the populous island of Oahu. They have the designation of H-X and connect military bases. Similarly, both Alaska and Puerto Rico have public roads that receive funding from the Interstate program, though these routes are not signed as Interstate Highways except "on paper". These roads are neither planned for nor currently built to Interstate Highway standards.
The numbering system can be summarized in these general rules. One- and two-digit highways are national routes:
★ 'Odd numbered' routes run north-south, and higher numbers are farther east.[8]
:'I-5' runs up and down the West Coast, with 'I-95' on the East Coast.
★ 'Even numbered' routes run east-west, and higher numbers are farther north.
:'I-10' runs along the Southern states, and 'I-90' runs near the US-Canada border.
Three-digit highways, or Auxiliary Interstate Highways, run only within a single city.
★ An 'odd first digit' signifies a spur route, which may begin at a large highway and terminate at a city center.
:'I-110' travels into downtown Los Angeles.
★ An 'even first digit' signifies a loop route around a city or a bypass through a city.
:'I-215' travels the perimeter of Salt Lake City.
:'I-895' serves as a bypass of downtown Baltimore.
★ The last two digits signify the highway's origin.
:'I-215' eventually returns to I-15, a primary interstate highway.
:'I-185' in Georgia leaves I-85 to go into Columbus.
★ Sometimes, a three-digit highway branches off another three-digit highway; this is called a tertiary spur route of a two-digit highway. Tertiary spurs do not meet their parent highways, but are associated with them via the three-digit highways they do meet.
:'I-370' in Maryland branches off I-270, and is thus a tertiary spur of I-70.
Primary routes
Interstate highways are typically known as 'Interstate XX' or 'I-XX', where "XX" is the one- or two-digit route number; sometimes 'Interstate Highway XX' ('IH XX') or 'Interstate Route XX' ('IR XX') is used. In some areas, the more generic 'Route XX' or 'Highway XX' is used, or in the case of southern California, Nevada, and New York, 'The XX'.
The numbering scheme for the Interstate Highway System (as well as the U.S. Highway System) was developed in 1957 by the American Association of State Highway and Transportation Officials (AASHTO) and is still coordinated by them, though their authority is occasionally trumped by a number written into Federal law. Within the continental United States, primary Interstates (also called main line Interstates or two-digit Interstates) are given one- or two-digit route numbers. Most Interstates have two digits; there are only three one-digit Interstates in the system: I-4, I-5 and I-8. Within this category, east-west highways are assigned even numbers, and north-south highways are assigned odd numbers. Odd route numbers increase from west to east, and even numbered routes increase from south to north, though there are exceptions to both principles in several locations. Numbers divisible by 5 are intended to be major among the primary routes, carrying traffic long distances. For example, I-5 runs from Canada to Mexico along the west coast (the only interstate to do so) while I-95 runs from Miami north to Canada along the east coast. In addition, I-10 runs from Santa Monica, California, to Jacksonville, Florida while I-90 runs from Seattle, to Boston. However, not all primary routes divisible by 5 traverse long distances. I-45 runs from Galveston, Texas, north to Dallas, a distance of only 284 miles (457 km). It is the only primary route divisible by 5 that does not cross state lines. See List of intrastate Interstate Highways for other primary routes that do not cross state lines.
I-50 and I-60 do not exist (and there are no even-numbered Interstates from 46 to 62), mainly because they would most likely have passed through the same states that already have US 50 and US 60. AASHTO rules discourage Interstate and US Highways having the same number within the same state, although I-24 and US 24 exist at opposite ends of Illinois. Some planned Interstates do not follow this guideline — I-69 will intersect US 69 in Lufkin, Texas[9], I-74 will overlap US 74 in North Carolina, and I-41 will do the same with US 41 in Wisconsin.
Several two-digit numbers are shared between two roads at opposite ends of the country, namely I-76, I-84, I-86 and I-88. Some of these were the result of a change in the numbering system in the 1970s; previously letter-suffixed numbers were used for long spurs off primary routes; for example, western I-84 was I-80N, as it went north from I-80. In the 1970s, AASHTO decided to eliminate these; some became additional two-digit routes, while others became three-digit routes (see below). Only two pairs of these exist; I-35 splits into I-35W and I-35E through both the Dallas-Fort Worth and the Minneapolis-St. Paul areas.
For the sake of efficiency, some Interstates double up for short or sometimes long distances. This is usually referred to as a ''concurrency'' or ''overlap''. One example is where I-75 and I-85 combine just below downtown Atlanta to form the Downtown Connector, a major thoroughfare through the city. Another example is the merging and diverging of Interstates 90 and 94, which double and then separate several times across the upper Midwest and Great Plains. I-90 and I-94 even join with I-39 from Madison to Portage, Wisconsin, creating the longest triple concurrence in the Interstate system. Interstates 90 and 80 are concurrent for almost 280 miles in Indiana and Ohio. A recent addition is the I-73/I-74 concurrency, which runs along U.S. Route 220 from Asheboro to Rockingham, North Carolina. I-73 will also share routes with I-40 and I-85 on the Greensboro Urban Loop, a new bypass route around Greensboro, North Carolina. Strict adherence to the directional nature of the system results in some amusing oddities. For a nine-mile (14 km) stretch east of Wytheville, Virginia, the driver can be traveling on both I-81 ''North'' and I-77 ''South'' at the same time (and vice versa) (see also Wrong-way concurrency).
Three-digit Interstates
Interstate 355, a tolled Interstate, beneath the Illinois Prairie Path in the west suburbs of Chicago.
Auxiliary Interstate Highways are given three-digit route numbers, which consist of a single digit prefixed to the two-digit number of a primary Interstate highway, to designate spur or loop routes branching from either the primary route or one of its other auxiliary routes. A spur route is one that deviates from its parent and does not end at another Interstate; it is given an odd first digit. A loop route is one that returns to its parent; it is given an even first digit. The number given to the first digit of a route that branches from the parent to end at another Interstate depends on the state; some consider these routes spurs and assign odd first digits, while others consider them loop connectors giving them even first digits.
When letter-suffixed two-digit Interstates (see above) were abundant, their auxiliary routes were given a number without a letter suffix (with the exception of I-180N in Boise, Idaho, which is now Interstate 184).
Due to the large number of these routes, auxiliary route (aka "spur route") numbers may be repeated in different states along the mainline; but no two three-digit Interstates in the same state can share a number. For instance, I-90 in New York alone has a full set of three-digit Interstates - I-190, I-290, I-390, I-490, I-590, I-690, I-790, I-890 and I-990.
Closed loops usually retain a single designation for the entire route, even when they enter other states. For example, Cincinnati, like many other cities, features a large loop around the city that intersects with the primary routes I-71, I-74, and I-75 and travels through Ohio, Kentucky, and Indiana. The entire 84 mile (135 km) loop is labeled I-275. (It is also the only three-digit interstate to ever go through three states.)
The loop highway around Washington, D.C., known as the Capital Beltway, carries both I-95 and I-495. Originally, the loop carried only I-495, in anticipation of I-95 being routed through Washington, but in 1977, I-95 was rerouted on the eastern half of the loop due to the cancellation of the segment that would have connected downtown Washington to College Park, Maryland, while I-495 remained on the western half. I-495 was added back to the eastern half of the loop in 1989, creating a rare concurrency of primary and auxiliary routes.
Unlike primary Interstates, three-digit Interstates are signed either east-west or north-south depending on the general orientation of the route, without any regard to the route number. For some looped Interstate routes, Inner and Outer banners are used as a directional labeling system as opposed to compass directions.
Of course, there are exceptions to these guidelines:
★ A contiguous loop surrounds the entire Minneapolis-St. Paul Metro area. I-94 intersects the loop in two spots and runs directly through it separating it into southern and northern halves; the southern half of it is labeled I-494 while the northern half of it is labeled I-694. The northern half rejoins I-94 approximately five miles before the southern half does; this stretch is signed I-94/I-694.
★ I-270 and I-255 form a beltway around the greater St. Louis area. On its southwest corner, I-270 becomes I-255 as it crosses I-55 counter-clockwise only to terminate back at I-270 in the northeast. In the early 1980s, local residents stopped a plan to designate the entire closed loop as I-270 and renumber the stub of I-270 from Glen Carbon to Edwardsville to I-870.
★ New York City has numerous spur routes off from I-78 and I-95, but none of I-78's spur routes actually intersect with I-78.
★ An auxiliary route numbered I-238 connects San Leandro and Castro Valley, California, yet there is no I-38. Instead, I-238 carries the designation of the portion of State Route 238 that the Interstate designation replaced. I-238's parent route is I-80, and at the time of I-238's designation, all child routes of I-80 (I-180 through I-980) were already designated in California.
Exceptions
A major exception to the overall numbering system is Interstate 99 in Pennsylvania, which was written into law as I-99 by Pennsylvania Congressman Bud Shuster; I-99 (which is also U.S. Route 220) is west of several Interstates that are numerically less than 99, but 99 was the nearest odd 2-digit number available for the interstate.
A less-notable exception is I-82, which lies fully north of I-84; this is a relic from I-84 previously having the designation of I-80N.
Some Proposed Interstate Highways have been given similarly non-conforming designations by their legislative proponents. For example, backers of the proposed Third Infantry Division Highway, a route in Georgia and Tennessee, have suggested it be named Interstate 3, in honor of the U.S. 3rd Infantry Division.
Other notable examples
The following two-digit Interstates change signed direction from their normal (even=east-west, odd=north-south) direction:
★ I-69 east of Lansing, Michigan
★ I-76 in Nebraska
The I-69 segment is an extension of its original route; I-76 only runs for two miles (3 km) in Nebraska before ending at I-80.
Two-digit Interstates in Hawaii, as well as the "paper" Interstates of Alaska and Puerto Rico, are numbered sequentially in order of funding, without regard to the rules on odd and even numbers.
Business Loop and Business Spur Interstates are not subject to any of the Interstate Highway standards. Their designation is simple - a Business Loop heads into a downtown area from its parent and returns to its parent; a Business Spur ends downtown, occasionally continuing from the end of the main Interstate. Business routes can split from either two- or three-digit Interstates, and can be repeated within a state. In a few cases, where an Interstate has been realigned, the old road has been designated a Business Loop because it is not up to standards.
Financing
I-15 near Downtown Salt Lake City. Five lanes in each direction with three-lane feeders on each side
About 56%[10] of the construction and maintenance costs are funded through user fees, primarily gasoline taxes, collected by states and the federal government, and tolls collected on toll roads and bridges. The rest of the costs are borne by the federal budget. In the eastern United States, large sections of some Interstate Highways planned or built prior to 1956 are operated as toll roads. The taxes dedicated to the construction and maintenance of highways are sometimes criticized as a direct subsidy from the government to promote and maintain auto-oriented development.
As American suburbs push ever outward, the costs incurred in maintaining freeway infrastructure have grown, leaving little in the way of funds for new interstate construction [11]. This has led to the proliferation of toll roads (turnpikes) as the new method of building limited-access highways in suburban areas. Also, some interstates are being privately maintained (e.g., VMS maintains I-35 in Texas) in order to cut rising costs of maintenance and allow state departments of transportation to focus on serving the fastest growing regions in their respective states. The future of the interstate system as we know it is in question. It is possible that parts of the system will have to be tolled in the future to meet maintenance and expansion demands, as has been done with adding toll HOV/HOT lanes in certain cities like San Diego, Salt Lake City, Minneapolis, Houston, Dallas, Atlanta and Washington, D.C.
The federal role in financing
The dominant role of the federal government in road finance has enabled it to achieve legislative goals that fall outside its power to regulate interstate commerce as enumerated in the federal Constitution. By threatening to withhold highway funds, the federal government has been able to stimulate state legislatures to pass a variety of laws. Although some object on the ground that this infringes on states' rights, the Supreme Court has upheld the practice as a permissible use of the Constitution's Commerce Clause.
The first major example was the introduction of the 55 mph (90 km/h) national speed limit in 1974. While its purpose was to save fuel in the wake of the 1973 energy crisis, federal speed controls stayed in effect for 21 years. The initial acceptance of the national speed limit emboldened various presidents and Congresses to enact additional pieces of legislation, some of which have little to do with highways or transportation. Examples include:
★ Increasing the legal drinking age to 21.[12]
★ Megan's Law legislation, requiring states to disclose identities of sex offenders.
★ Lowering the legal intoxication level to 0.08%.
★ Requiring the use of carpool (HOV) lanes.
States must also meet minimum enforcement standards for all federally-mandated legislation (for example, minimum penalties for violation of these laws and a minimum number of per capita underage drinking convictions or a compelling explanation regarding why this number is not met). This has proved to be controversial. Supporters hold that it is a way to provide an impetus to states to pass uniform legislation. Critics maintain that using highway dollars in this fashion upsets the balance between federal and states rights in favor of the federal government, and effectively holds funds as ransom in order to coerce state governments into passing laws that would not have otherwise been introduced. Some have even argued that the current arrangement is unconstitutional. Law enforcement agencies in some states argue that efforts to meet quotas for underage drinking convictions have distracted them from other matters and strained relations with those under 21. Any state that was to lose federal highway funding would quickly face deteriorating infrastructure, fiscal impoverishment, or both.
Of course, a state that lost federal highway funding ''could'' theoretically threaten to stop maintaining its highways, if that were politically palatable to its residents.
Local maintenance
A few Interstates are maintained by local authorities:
★ Baltimore, Maryland: Interstate 70 and Interstate 83 in the city limits[13]
★ New York City: Small portions of Interstate 278[14]
★ Washington, D.C.: As the city and District are identical, the District maintains the portions of Interstate 66, Interstate 295, Interstate 395 and Interstate 695 inside the city.
Non-chargeable Interstate routes
In addition to Interstate highways financed with federal funds (Chargeable Interstate routes), federal laws allow other highways to be signed as Interstates, if they meet the Interstate Highway standards and are logical additions or connections to the System.
Called Non-Chargeable Interstate routes, these additions fall under two categories:
# Routes that already meet Interstate standards. These may immediately be signed as Interstates once their proposed number is approved, or may be retained with a non-Interstate designation.
# Routes not yet upgraded to Interstate standards. These cannot be signed as Interstates until they have been fully upgraded.
Signage
The majority of Interstates have exit numbers. All traffic signs and lane markings on the Interstates are supposed to be designed in compliance with the Manual on Uniform Traffic Control Devices (MUTCD). However, there are many local and regional variations in signage.
For many years, California was the only state that did not use an exit numbering system. It was granted an exemption in the 1950s due to having an already largely completed and signed highway system; at the time, placing exit number signage on the signs across the state was deemed too expensive. Since 2002, however, California has begun to incorporate exit numbers on all of its freeways - interstate, U.S., and state routes alike. To mitigate costs, a common occurrence is for Caltrans to install exit number signage only when a freeway or interchange is built, reconstructed, retrofitted, or repaired. The majority of the exits along Interstates 5, 10, and 80 now have exit number signage, particularly in rural areas.
In most states, the exit numbers correspond to the mileage markers on the Interstates (with an exception being I-19 in Arizona, whose length is measured in kilometers instead of miles). On even-numbered Interstates, mileage count increases to the east and decreases to the west (except on the I-90 portion of the New York State Thruway, I-90 between Chicago and Rockford, IL, the I-190 spur into O'Hare International Airport in Chicago, and the portion of I-76 in New Jersey, all of which count up going west); and on odd-numbered Interstates, mileage count increases to the north and decreases to the south and the exit numbers increase and decrease accordingly.
Many northeastern states label exit numbers sequentially, regardless of how many miles have passed between exits. States in which Interstate exits are still numbered sequentially are: Connecticut, Delaware, Massachusetts, New Hampshire, New York, Rhode Island and Vermont. Maine, Pennsylvania, Virginia, Georgia, and Florida followed this system for a number of years, but recently converted to having the exit numbers correspond to mileage markers. The Pennsylvania Turnpike uses both the mile marker number and the sequential number. The mile marker number is used for signage, while the sequential number is used for numbering interchanges internally. The New Jersey Turnpike also has sequential numbering, but other interstates within New Jersey generally use mile markers.
The Interstate shield
A sample Interstate 95 shield.
Interstate Highways are signed by a number on a trademarked red, white and blue sign as shown to the right. In the original design, the state was listed above the highway number, but in many states, this area is now left blank. The sign itself usually measures 36 inches (91 cm) high , and is 36 inches wide for two-digit interstates or 45 inches (114 cm) for three-digit interstates.
Business Loop and Business Spur Interstates use a special shield where the red and blue are replaced with green; the word BUSINESS appears instead of INTERSTATE, and the word SPUR or LOOP usually appears above the number.
Map of states that use shields with the state name within.
Blue: All state shields.
Turquoise: Mix of both state and neutral shields.
White: All neutral shields.
Blue: All state shields.
Turquoise: Mix of both state and neutral shields.
White: All neutral shields.
All general shields
Many states have few or no shields with the name of the state, such as Washington, Oregon, Idaho, Ohio, Nevada, Utah, Indiana and Illinois. Many times, older state-name shields can only be found at areas isolated from the highway network, such as rural municipalities or in urban areas away from the actual interstate (e.g. the Interstate 4 state-name shield remaining in Orlando). States like New York, Delaware, New Hampshire, Pennsylvania, have almost no state-name shields remaining.
Some state shields, some neutral shields
Many states are in the process of switching from state-named shields to neutral shields, resulting in a mix of some state shields and the more recent general shields. Numerous southeastern states have been neutering the shields ever since the mid to late 1990s, and some began in 2000. Louisiana began neutering the shields ever since the 1990s. In Alabama the recently-made shields are neutral shields. One can still find many state shields in some cities, but some highways with newer signage have neutral shields. TxDOT started neutering the shields in the early 2000s. In northeastern Texas most of the shields are neutral. In southeastern Texas, one might still see many state shields. Interstate 635 state shields might still be found, but most 3-digit interstate shields lack state names.
All or most state shields
States such as California, Arizona, New Mexico, Oklahoma, Missouri, and even Iowa and Maryland still use shields with the state name. In California, many recently placed interstate shields still use the state name (mostly in the metropolitan cities, especially the 3-digit interstate highways). In Kansas, KDOT still uses the state-name shields while the KTA does not. You still find almost all the interstates in Metropolitan Oklahoma City, Kansas City and Metropolitan St. Louis still use interstate shields with state name printed, even those new ones. In Iowa and Maryland there are still many shields with the state name.
Extremes
The most heavily traveled area of the Interstate Highway system is the 405 Freeway in Seal Beach, California, with a 2002 estimate of 377,000 vehicles a day. The least traveled section is Interstate 95 just north of Houlton, Maine (near the Canadian border), with 1,880 vehicles a day (2001 estimate).
The most extreme directional points of the Interstate Highway system are:
★ Northernmost-the northern termini of Interstates 5, 15, and 29, crossing the Canadian border at the 49th parallel near, respectively, Blaine, Washington, Sweetgrass, Montana, and Pembina, North Dakota.
★ Southernmost-a bend on Interstate H-1 in the Kaimuki section of Honolulu, Hawaii, less than half a mile (0.8 km) before its eastern terminus (lat. 21.3 deg. N.). The southernmost point in the 48 contiguous states is the southern terminus of Interstate 95 in Miami, Florida (lat. 25.8 deg. N.).
★ Easternmost-the northern terminus of Interstate 95 near Houlton, Maine, at the border of New Brunswick in Canada (long. 67.8 deg. W.).
★ Westernmost-the western terminus of Interstate H-1 in Kapolei, Hawaii (long. 158.06 deg. W.). The westernmost point in the contiguous states is a curve on Interstate 5 near Wolf Creek, Oregon (long. 123.23 deg. W.).
The highest point on the Interstate Highway System is at the Eisenhower Tunnel on Interstate 70 in the Rocky Mountains of Colorado, at the Continental Divide (elev. 11,158 feet (3401 m)). The lowest point is on Interstate 8 at the New River near Seeley, California (elev. -52 feet (-16 m)).
The longest Interstate highway is Interstate 90, which runs 3099 miles (4 987 km) between Boston, Massachusetts and Seattle, Washington. The longest north-south Interstate highway is generally cited as Interstate 95; when completed, it will run 1927 mi (3 101 km) between Miami, Florida and the Canadian border (there is a gap in New Jersey). The shortest Interstate is Interstate 878, a 0.7-mile (1.1 km) portion of New York State Route 878 adjacent to John F. Kennedy International Airport in Queens, New York. However, it is not officially signed. The shortest signed Interstate is Interstate 375 in downtown Detroit, Michigan, at 1.06 miles (1.71 km).
Criticism
John Steinbeck, in his travelogue ''Travels With Charley'', claimed "When we get these thruways across the whole country, as we will and must, it will be possible to drive from New York to California without seeing a single thing." Charles Kuralt echoed this statement in his biography ''A Life on the Road'': "The interstate highway system is a wonderful thing. It makes it possible to go from coast to coast without seeing anything or meeting anybody. If the United States interests you, stay off the interstates." These quotes refer to the tendency of Interstate highways to emphasize more rapid, uninterrupted transportation than other road networks. This could be contrasted to the sometimes-romanticized perception of state and county routes, often two-lane highways, that may offer more chances to stop at local small businesses or see true rural America.
References
1. Attachment V, Ownership and Maintenance Agreement for the Wilson Bridge, Woodrow Wilson Bridge Initial Financial Plan
2. Table 1-36: Long-Distance Travel in the United States by Selected Trip Characteristics
3. Annual Vehicle Distance Traveled in Miles and Related Data
4.
5. Traveling interstates is our sixth freedom Al Neuharth
6. http://www.snopes.com/autos/law/airstrip.asp
7. ONE MILE IN FIVE: Debunking the Myth
8. ''The Dwight D. Eisenhower National System of Interstate and Defense Highways, Route Log and Finder List'', FHWA, March 2001
9. Interactive map
10. http://www.fhwa.dot.gov/policy/ohim/hs03/htm/hf10.htm 2003 FHWA summary
11. Field, David. "On 40th birthday, interstates face expensive midlife crisis." ''Insight on the News'', 29 July 1996, 40-42.
12. [South Dakota v. Dole]
13.
14. New York State Department of Transportation - Region 11 (New York City) Built and Unbuilt Arterial System
See also
★ Contraflow
★ Gas tax
★ Highway patrol
★ Non-motorized vehicle access on freeways
★ List of roads and highways
★ Mile-log
★ Parkway
★ List of major freeway systems
★ Interstate Highway System chronology
★ Adopt a Highway
External links
★ Interstate-Guide.com@Interstate shield galleries
★ Interstate Highway information
★ FHWA Route Log and Finder List
★ FHWA Turner-Fairbank Highway Research Center - Analysis and History of Interstate Highway System
★ History of urban interstates - Norton, "Fighting Traffic: U.S. Transportation Policy and Urban Congestion, 1955-1970"
★ 3-digit Interstate Highways
★ Pictures of all Interstates
★ One of 100 milestone documents of American history
★ Federal Highway Administration's article on the act
★ ''Fortune'' magazine on history of the Interstate Highway System
★ Tony Graham's Exit List Collection A compilation of all Interstate exit lists available online
★ Another great Interstate Page, with facts on all 2-digit Interstates and links to their exit lists
★ Highway Heaven Contains exit lists for most Interstate highways
★ RoadGeek - A complete set of TrueType fonts for simulating Interstate and other highway signage
★ 2006: 50th Anniversary of the Interstate Highway System Celebration - from the American Road & Transportation Builders Association
★ Interstate50th.org - A website that celebrates the system's golden anniversary, filled with facts and other interesting information about the highways, such as where the first miles of Interstate were built
This article provided by Wikipedia. To edit the contents of this article, click here for original source.
psst.. try this: add to faves
