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8. Security - check for the yellow padlock on the Interstate Highway System site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Interstate Highway System, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Interstate Highway System, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.

in California, with two lanes in each direction separated by a large grassy median (highway), 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 Dwight D. Eisenhower who was in office when the system was created. The Interstate Highway System is a separate system within the larger National Highway System (United States). The entire system, as of 2004, had a total length of 46,837 miles (75,376 km) .

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 (Capital Beltway), 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 .

The system serves nearly all major U.S. cities. Unlike counterparts in most other industrialized countries, many Interstates pass through Central Business District 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; of these trips, about one-third (by the total number of miles driven in the country in 2003) utilize the Interstate system.

History 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 Germany autobahn network - as a necessary component of a national defense system. 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 United States Army to provide it with a list of roads it considered necessary for national defense, resulting in the Pershing Map.McNichol, Dan. The Roads that Built America: The Incredible Story of the U.S. Interstate System. New York: Sterling Publishing Co., Inc., 2006. ISBN 1-4027-3468-9 Later that decade, highways such as the Parkways in New York State 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. In 1938, President Franklin D. Roosevelt gave BPR chief Thomas MacDonald a hand-drawn map of the U.S. marked with eight superhighway corridors for study. 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. .

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 and taking 35 years to complete .

However, due to the cancellation of the Somerset Freeway, Interstate 95 in New Jersey 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.

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 List of gaps in Interstate Highways, 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 (100 to 130 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 lane reversal, was first employed in the 1998 evacuation of New Orleans, Louisiana, in preparation for Hurricane Georges. In 2004, contraflow was employed ahead of Hurricane Charley in the Tampa, Florida area and on the Gulf Coast before the landfall of Hurricane Ivan.{{cite web], and Houston, Texas, prior to hurricanes Hurricane Katrina and Hurricane 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. http://www.snopes.com/autos/law/airstrip.asp

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.

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: Interstate 4, Interstate 5 and Interstate 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 Division (mathematics) by 5 are intended to be major among the primary routes, carrying traffic long distances. For example, Interstate 5 runs from Canada to Mexico along the west coast (the only Interstate to do so) while Interstate 95 runs from Miami, Florida north to Canada along the east coast. In addition, Interstate 10 runs from Santa Monica, California, to Jacksonville, Florida, while Interstate 90 runs from Seattle, Washington, to Boston, Massachusetts. However, not all primary routes divisible by 5 traverse long distances. Interstate 45 runs from Galveston, Texas, north to Dallas, Texas, 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 U.S. Route 50 and U.S. Route 60. AASHTO rules discourage Interstate and U.S. Highways having the same number within the same state, although Interstate 24 and U.S. Route 24 exist at opposite ends of Illinois. Some planned Interstates do not follow this guideline — Interstate 69 will intersect U.S. Route 69 in Lufkin, Texas Interactive map, Interstate 74 will overlap U.S. Route 74 in North Carolina, and Interstate 41 will do the same with U.S. Route 41 in Wisconsin.

Several two-digit numbers are shared between two roads at opposite ends of the country, namely Interstate 76 (disambiguation), Interstate 84 (disambiguation), Interstate 86 (disambiguation) and Interstate 88 (disambiguation). 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 Interstate 84 (west) was I-80N, as it went north from Interstate 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 still exist; Interstate 35 splits into Interstate 35W (disambiguation) and Interstate 35E (disambiguation) through both the Dallas Fort Worth Metroplex 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 (road) or overlap. One example is where Interstate 75 and Interstate 85 combine near downtown Atlanta, Georgia to form the Downtown Connector, a major thoroughfare through the city. Another example is the merging and diverging of Interstates Interstate 90 and Interstate 94, which double and then separate several times across the upper Midwest and Great Plains. I-90 and I-94 even join with Interstate 39 from Madison, Wisconsin to Portage, Wisconsin, creating the longest triple concurrence in the Interstate system. Interstates 90 and Interstate 80 are concurrent for almost 280 miles in Indiana and Ohio. A recent addition is the Interstate 73/Interstate 74 concurrency, which runs along U.S. Route 220 from Asheboro, North Carolina to Rockingham, North Carolina. I-73 will also share routes with Interstate 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 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 Interstates , 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 (a.k.a. "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 - Interstate 190 (New York), Interstate 290 (New York), Interstate 390, Interstate 490 (New York), Interstate 590, Interstate 690, Interstate 790, Interstate 890 and Interstate 990.

Closed loops usually retain a single designation for the entire route, even when they enter other states. For example, Cincinnati, Ohio, 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 Interstate 275 (Ohio). (It is also the only three-digit interstate to ever go through three states. With the possible exception of I-495 which briefly enters the non-state Washington, DC.)

The loop highway around Washington, D.C., known as the Capital Beltway, carries both Interstate 95 and Interstate 495 (Capital Beltway). 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/Outer labeling are used as a directional labeling system as opposed to compass directions.

Of course, there are exceptions to these guidelines:

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 Interstate 82, which lies fully north of Interstate 84 (west); 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 (U.S. state) 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: 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 near Downtown Salt Lake City. Five lanes in each direction with three-lane feeders on each side

About 56%http://www.fhwa.dot.gov/policy/ohim/hs03/htm/hf10.htm 2003 FHWA summary 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 Field, David. "On 40th birthday, interstates face expensive midlife crisis." Insight on the News, 29 July 1996, 40-42.. 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. 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, California, Salt Lake City, Utah, Minneapolis, Minnesota, Houston, Texas, Dallas, Texas, Atlanta, Georgia{{cite web|url=http://www.cobbrides.com/pdfs/1st%20toll%20project%20proposed%20for%20I.pdf|title=1st toll project proposed for I-20 eastPlan would add lanes outside I-285|author=Ariel Hart|publisher=Atlanta Journal-Constitution|accessdate=2007-09-27--> 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 United States 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 of the United States has upheld the practice as a permissible use of the Constitution's Commerce Clause.

The first major example was the introduction of the National Maximum Speed Law 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:

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:

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 California Department of Transportation to install exit number signage only when a freeway or interchange is built, reconstructed, retrofitted, or repaired. The majority of the exits along Interstates Interstate 5, Interstate 10 in California, and Interstate 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 Interstate 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 Interstate 90 portion of the New York State Thruway, I-90 between Chicago and Rockford, IL, the Interstate 190 (Illinois) spur into O'Hare International Airport in Chicago, and the portion of Interstate 76 (east) 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 shield.

    Interstate Highways are signed by a number on a trademarked red, white and blue Highway shield 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.

    Extremes The most heavily traveled area of the Interstate Highway system is the Interstate 405 (California) in Los Angeles, California, with a 2005 estimate of 382,000 vehicles a day.http://www.timeforkids.com/TFK/teachers/wr/article/0,27972,1099514,00.html The least traveled section is Interstate 95 in Maine 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:

    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 (California) 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 United States-Canada border (there is a gap in New Jersey). The shortest, albeit unsigned, 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. The shortest signed Interstate is Interstate 375 (Michigan) in downtown Detroit, Michigan, at 1.06 miles (1.71 km).

    References See also

    External links

    in California, with two lanes in each direction separated by a large grassy median (highway), 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 Dwight D. Eisenhower who was in office when the system was created. The Interstate Highway System is a separate system within the larger National Highway System (United States). The entire system, as of 2004, had a total length of 46,837 miles (75,376 km) .

    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 (Capital Beltway), 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 .

    The system serves nearly all major U.S. cities. Unlike counterparts in most other industrialized countries, many Interstates pass through Central Business District 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; of these trips, about one-third (by the total number of miles driven in the country in 2003) utilize the Interstate system.

    History 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 Germany autobahn network - as a necessary component of a national defense system. 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 United States Army to provide it with a list of roads it considered necessary for national defense, resulting in the Pershing Map.McNichol, Dan. The Roads that Built America: The Incredible Story of the U.S. Interstate System. New York: Sterling Publishing Co., Inc., 2006. ISBN 1-4027-3468-9 Later that decade, highways such as the Parkways in New York State 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. In 1938, President Franklin D. Roosevelt gave BPR chief Thomas MacDonald a hand-drawn map of the U.S. marked with eight superhighway corridors for study. 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. .

    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 and taking 35 years to complete .

    However, due to the cancellation of the Somerset Freeway, Interstate 95 in New Jersey 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.

    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 List of gaps in Interstate Highways, 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 (100 to 130 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 lane reversal, was first employed in the 1998 evacuation of New Orleans, Louisiana, in preparation for Hurricane Georges. In 2004, contraflow was employed ahead of Hurricane Charley in the Tampa, Florida area and on the Gulf Coast before the landfall of Hurricane Ivan.{{cite web], and Houston, Texas, prior to hurricanes Hurricane Katrina and Hurricane 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. http://www.snopes.com/autos/law/airstrip.asp

    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.

    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: Interstate 4, Interstate 5 and Interstate 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 Division (mathematics) by 5 are intended to be major among the primary routes, carrying traffic long distances. For example, Interstate 5 runs from Canada to Mexico along the west coast (the only Interstate to do so) while Interstate 95 runs from Miami, Florida north to Canada along the east coast. In addition, Interstate 10 runs from Santa Monica, California, to Jacksonville, Florida, while Interstate 90 runs from Seattle, Washington, to Boston, Massachusetts. However, not all primary routes divisible by 5 traverse long distances. Interstate 45 runs from Galveston, Texas, north to Dallas, Texas, 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 U.S. Route 50 and U.S. Route 60. AASHTO rules discourage Interstate and U.S. Highways having the same number within the same state, although Interstate 24 and U.S. Route 24 exist at opposite ends of Illinois. Some planned Interstates do not follow this guideline — Interstate 69 will intersect U.S. Route 69 in Lufkin, Texas Interactive map, Interstate 74 will overlap U.S. Route 74 in North Carolina, and Interstate 41 will do the same with U.S. Route 41 in Wisconsin.

    Several two-digit numbers are shared between two roads at opposite ends of the country, namely Interstate 76 (disambiguation), Interstate 84 (disambiguation), Interstate 86 (disambiguation) and Interstate 88 (disambiguation). 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 Interstate 84 (west) was I-80N, as it went north from Interstate 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 still exist; Interstate 35 splits into Interstate 35W (disambiguation) and Interstate 35E (disambiguation) through both the Dallas Fort Worth Metroplex 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 (road) or overlap. One example is where Interstate 75 and Interstate 85 combine near downtown Atlanta, Georgia to form the Downtown Connector, a major thoroughfare through the city. Another example is the merging and diverging of Interstates Interstate 90 and Interstate 94, which double and then separate several times across the upper Midwest and Great Plains. I-90 and I-94 even join with Interstate 39 from Madison, Wisconsin to Portage, Wisconsin, creating the longest triple concurrence in the Interstate system. Interstates 90 and Interstate 80 are concurrent for almost 280 miles in Indiana and Ohio. A recent addition is the Interstate 73/Interstate 74 concurrency, which runs along U.S. Route 220 from Asheboro, North Carolina to Rockingham, North Carolina. I-73 will also share routes with Interstate 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 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 Interstates , 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 (a.k.a. "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 - Interstate 190 (New York), Interstate 290 (New York), Interstate 390, Interstate 490 (New York), Interstate 590, Interstate 690, Interstate 790, Interstate 890 and Interstate 990.

    Closed loops usually retain a single designation for the entire route, even when they enter other states. For example, Cincinnati, Ohio, 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 Interstate 275 (Ohio). (It is also the only three-digit interstate to ever go through three states. With the possible exception of I-495 which briefly enters the non-state Washington, DC.)

    The loop highway around Washington, D.C., known as the Capital Beltway, carries both Interstate 95 and Interstate 495 (Capital Beltway). 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/Outer labeling are used as a directional labeling system as opposed to compass directions.

    Of course, there are exceptions to these guidelines:

    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 Interstate 82, which lies fully north of Interstate 84 (west); 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 (U.S. state) 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: 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 near Downtown Salt Lake City. Five lanes in each direction with three-lane feeders on each side

    About 56%http://www.fhwa.dot.gov/policy/ohim/hs03/htm/hf10.htm 2003 FHWA summary 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 Field, David. "On 40th birthday, interstates face expensive midlife crisis." Insight on the News, 29 July 1996, 40-42.. 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. 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, California, Salt Lake City, Utah, Minneapolis, Minnesota, Houston, Texas, Dallas, Texas, Atlanta, Georgia{{cite web|url=http://www.cobbrides.com/pdfs/1st%20toll%20project%20proposed%20for%20I.pdf|title=1st toll project proposed for I-20 eastPlan would add lanes outside I-285|author=Ariel Hart|publisher=Atlanta Journal-Constitution|accessdate=2007-09-27--> 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 United States 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 of the United States has upheld the practice as a permissible use of the Constitution's Commerce Clause.

    The first major example was the introduction of the National Maximum Speed Law 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:

    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:

    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 California Department of Transportation to install exit number signage only when a freeway or interchange is built, reconstructed, retrofitted, or repaired. The majority of the exits along Interstates Interstate 5, Interstate 10 in California, and Interstate 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 Interstate 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 Interstate 90 portion of the New York State Thruway, I-90 between Chicago and Rockford, IL, the Interstate 190 (Illinois) spur into O'Hare International Airport in Chicago, and the portion of Interstate 76 (east) 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 shield.

    Interstate Highways are signed by a number on a trademarked red, white and blue Highway shield 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.

    Extremes The most heavily traveled area of the Interstate Highway system is the Interstate 405 (California) in Los Angeles, California, with a 2005 estimate of 382,000 vehicles a day.http://www.timeforkids.com/TFK/teachers/wr/article/0,27972,1099514,00.html The least traveled section is Interstate 95 in Maine 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:

    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 (California) 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 United States-Canada border (there is a gap in New Jersey). The shortest, albeit unsigned, 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. The shortest signed Interstate is Interstate 375 (Michigan) in downtown Detroit, Michigan, at 1.06 miles (1.71 km).

    References See also

    External links



    Interstate Highway System - Wikipedia, the free encyclopedia
    The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly called the Interstate Highway System (or simply, the Interstate System), is a network of ...

    Category:Interstate Highway System - Wikipedia, the free encyclopedia
    Subcategories. This category has the following 44 subcategories, out of 44 total. [+]

    Interstate System - Design - FHWA
    Context Sensitive Solutions; Design Awards; Design Standards; Interstate System; Subsurface Utility Engineering; Utility Program; Value Engineering; Dwight D.

    50th Anniversary of the Interstate Highway System Home Page
    J. Richard Capka: I invite you to explore this Web site devoted to the Dwight D. Eisenhower System of Interstate and Defense Highways on its 50th anniversary.

    Interstate Highway System
    Persons travelling through the United States today may find it difficult to imagine our country without the Eisenhower Interstate Highway System.

    Category:Interstate Highways - Wikimedia Commons
    An Interstate Highway is a road in the Dwight D. Eisenhower National System of Interstate and Defense Highways in the United States.

    PUBLIC ROADS On-Line (Summer 1996) - Federal-Aid Highway Act of 1956 ...
    Summer 1996· Vol. 60· No. 1. Go to the Public Roads Web site Federal-Aid Highway Act of 1956: CREATING THE INTERSTATE SYSTEM by Richard F. Weingroff

    Welcome to Interstate-Guide.com!
    Interstate highway guide including photos, statistics, history, and descriptions ... Welcome to Interstate-Guide.com: Welcome to Interstate-Guide.com, brought to you by AARoads!

    The effect of trade on the demand for skill - evidence from the ...
    The Interstate Highway System was designed to connect major metropolitan areas, to serve national defense and to connect the United States to Canada and Mexico.

    The effect of trade on the demand for skill: evidence from the ...
    The Interstate Highway System was designed to connect major metropolitan areas, to serve national defense and to connect the United States to Canada and Mexico.

     

    Interstate Highway System



     
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