Dwight D. Eisenhower National System of Interstate and Defense Highways
Highway shields for Interstate 80 and Business Loop Interstate 80
Interstate Highways in the 48 contiguous states
System information
Formed:	June 29, 1956[1]
Length:	47,182 mi[a] (75,932 km)
Highway names
Interstates:	Interstate X (I-X)
System links
Interstate Highway System Main • Auxiliary • Business

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 known as the Interstate Highway System, Interstate Freeway System or the Interstate) is a network of limited-access roads, including freeways, highways, and expressways, forming part of the National Highway System of the United States. The system is named for President Dwight D. Eisenhower, who championed its formation. Construction was authorized by the Federal Aid Highway Act of 1956, and the original portion was completed 35 years later. The network has since been extended, and as of 2010^[update], it had a total length of 47,182 miles (75,932 km).^[2] As of 2010^[update], about one-quarter of all vehicle miles driven in the country use the Interstate system.^[3] The cost of construction has been estimated at $425 billion (in 2006 dollars),^[4] making it the "largest public works program since the Pyramids."^[5]

History[link]

Planning[link]

	Remarks in Cadillac Square, Detroit President Eisenhower delivered remarks about the need for a new highway program at Cadillac Square in Detroit on October 29, 1954 Text of speech excerpt
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The Interstate Highway System had been lobbied for by major U.S. automobile manufacturers and championed by President Dwight D. Eisenhower, who was influenced by his experiences as a young Army officer crossing the country in the 1919 Army Convoy on the Lincoln Highway, the first road across America.

Initial federal planning for a nationwide highway system began in 1921 when the Bureau of Public Roads asked the Army to provide a list of roads it considered necessary for national defense. This resulted in the Pershing Map.^[6] Later that decade, highways such as the New York parkway system were built as part of local or state highway systems.

As automobile traffic increased, planners saw a need for such an interconnected national system to supplement the existing, largely non-freeway, United States Numbered Highways system. By the late 1930s, planning had expanded to a system of new superhighways.

In 1938, President Franklin D. Roosevelt gave Thomas MacDonald, chief at the Bureau of Public Roads, a hand-drawn map of the U.S. marked with eight superhighway corridors for study.^[6] In 1939, Bureau of Public Roads Division of Information chief Herbert S. Fairbank wrote a report entitled Toll Roads and Free Roads, "the first formal description of what became the interstate highway system," and in 1944 the similarly themed Interregional Highways.^[7][8]

Eisenhower gained an appreciation of the German Autobahn network as a necessary component of a national defense system while he was serving as Supreme Commander of the Allied forces in Europe during World War II.^[9] He recognized that the proposed system would also provide key ground transport routes for military supplies and troop deployments in case of an emergency or foreign invasion.

1955 map: The planned status of U.S. highways in 1965, as a result of the developing Interstate Highway System

I-55 under construction in Mississippi, photo from May, 1972

The publication in 1955 of the General Location of National System of Interstate Highways, informally known as the Yellow Book, mapped out what became the Interstate System.^[10] Assisting in the planning was Charles Erwin Wilson, who was still head of General Motors when President Eisenhower selected him as Secretary of Defense in January 1953.

Construction[link]

The Interstate Highway System was authorized by the Federal Aid Highway Act of 1956^[11] – popularly known as the National Interstate and Defense Highways Act of 1956 – on June 29.

Three states have claimed the title of first Interstate Highway. Missouri claims that the first three contracts under the new program were signed in Missouri on August 2, 1956. The first contract signed was for U.S. 66. On August 13, 1956, Missouri awarded the first contract based on new Interstate Highway funding.^[12]

Kansas claims that it was the first to start paving after the act was signed. Preliminary construction had taken place before the act was signed, and paving started September 26, 1956. The state marked its portion of I-70 as the first project in the United States completed under the provisions of the new Federal-Aid Highway Act of 1956.^[12]

According to information liaison specialist Richard Weingroff, the Pennsylvania Turnpike could also be considered one of the first Interstate Highways. On October 1, 1940, 162 miles (261 km) of the highway now designated I-70 and I-76 opened between Irwin and Carlisle. The Commonwealth of Pennsylvania refers to the turnpike as the Granddaddy of the Pikes.^[12]

Milestones in the construction of the Interstate Highway System include:

• October 17, 1974 – Nebraska becomes the first state to complete all of its mainline interstate highways with the dedication of its final piece of Interstate 80.^[13]
• August 22, 1986 – The final section of the coast-to-coast (San Francisco to New York metropolitan area) Interstate 80 is dedicated on the western edge of Salt Lake City. The section spanned from Redwood Road to just west of the Salt Lake City International Airport. At the dedication it was noted that co-incidentally this was only 50 miles (80 km) from Promontory Summit, where the golden spike of the United States First Transcontinental Railroad was laid 120 years prior.^[14][15][16]
• August 10, 1990 – The final section of coast-to-coast Interstate 10 (Santa Monica, California to Jacksonville, Florida) is dedicated. This section includes the Papago Freeway Tunnel under downtown Phoenix, Arizona. Completion of this section was delayed due to a freeway revolt that forced the cancellation of an originally planned elevated routing.^[17]
• September 12, 1991 – Interstate 90 becomes the final coast-to-coast Interstate Highway (Seattle to Boston) to be completed with the dedication of an elevated viaduct bypassing Wallace, Idaho. This section was delayed after residents forced the cancellation of the originally planned at-grade alignment that would have demolished much of downtown Wallace. The residents accomplished this feat by placing the most of the downtown area on the National Register of Historic Places; blocking the path of the original alignment. After the dedication residents held a mock funeral celebrating the removal of the last stoplight on a transcontinental Interstate Highway.^[17][18]
• October 14, 1992 – The original Interstate Highway system is proclaimed to be complete with the opening of Interstate 70 through Glenwood Canyon. This section is considered an engineering marvel with a 12-mile (19 km) span featuring 40 bridges and numerous tunnels and is one of the most expensive rural highways per mile.^[19][20]

The initial cost estimate for the system was $25 billion over 12 years; it ended up costing $114 billion (adjusted for inflation, $425 billion in 2006 dollars^[4]) and took 35 years.^[21]

1992–present[link]

Additional spurs and loops/bypasses remain under construction, such as Interstate 485 in North Carolina, which has been under construction since the 1980s. A few main routes not part of the original plan remain under construction, such as Interstate 22 in Tennessee, Mississippi, and Alabama and the extension of Interstate 69 from Indiana to Texas. Officials have also identified some non-Interstate corridors for future inclusion into the system, either by construction of new Interstate routes or upgrade of existing roads to Interstate standards.

Due to the cancellation of the Somerset Freeway, Interstate 95 is discontinuous in New Jersey. Authorized by the federal government in 2004, the Pennsylvania Turnpike/Interstate 95 Interchange Project is scheduled to connect the separate sections of I-95 to form a continuous route, completing the final section of the original plan. Construction began in 2010.^[22]

Standards[link]

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. 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[link]

Being freeways, Interstate Highways usually have the highest speed limits in a given area. Speed limits are determined by individual states. From 1974 to 1987, the maximum speed limit on any highway in the United States was 55 miles per hour (89 km/h), in accordance with federal law.^[23] Currently, rural speed limits generally range from 65 to 75 miles per hour (105 to 121 km/h), although several portions of I-10 and I-20 in rural western Texas have speed limits of 80 mph (129 km/h), the highest in the nation as of September 2011 after the passage of that state's House Bill 1201. Portions of I-15 in rural central Utah have a speed limit of 80 mph (129 km/h). Typically, lower limits are established in the more densely populated Northeastern states, while higher speed limits are established in the less densely populated Southern and Western states.^[24] For example, the maximum speed limit is 75 mph (121 km/h) in Maine, 65 mph (105 km/h) from New Hampshire to New Jersey, and 50 mph (80 km/h) in the District of Columbia.^[24] In some areas, speed limits on Interstates can be significantly lower in areas where they traverse significantly hazardous areas. I-90 has a maximum speed limit of 50 mph (80 km/h) in downtown Cleveland because of two sharp curves with a suggested limit of 35 mph (56 km/h) in a heavily congested area, I-70 through Wheeling, West Virginia, has a maximum speed limit of 45 mph (72 km/h) through the Wheeling Tunnel and most of downtown Wheeling, and I-68 has a maximum speed limit of 40 mph (64 km/h) through Cumberland, Maryland, because of multiple hazards including sharp curves and narrow lanes through the city.

Other uses[link]

As one of the components of the National Highway System, Interstate Highways improve the mobility of military troops to and from airports, seaports, rail terminals, and other military bases. Interstate Highways also connect to other roads that are a part of the Strategic Highway Network, a system of roads identified as critical to the U.S. Department of Defense.^[25]

The system has also 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, has been employed several times for hurricane evacuations. After public outcry regarding the inefficiency of evacuating from southern Louisiana prior to Hurricane Georges' landfall in September 1998, government officials looked towards contraflow to improve evacuation times. In Savannah, Georgia, and Charleston, South Carolina, in 1999, lanes of Interstates 16 and 26 were used in a contraflow configuration in anticipation of Hurricane Floyd with mixed results.^[26]

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;^[27] however, evacuation times there were no better than previous evacuation operations. Engineers began to apply lessons learned from the analysis of prior contraflow operations, including limiting exits, removing troopers (to keep traffic flowing instead of having drivers stop for directions), and improving the dissemination of public information. As a result, the 2005 evacuation of New Orleans, Louisiana prior to Hurricane Katrina ran far more smoothly.^[28]

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.^[29][30]

Numbering system[link]

I-78 and US 22 in Berks County, Pennsylvania

Primary (one- and two-digit) routes[link]

The numbering scheme for the Interstate Highway System was developed in 1957 by the American Association of State Highway and Transportation Officials (AASHTO). The association's present numbering policy dates back to August 10, 1973.^[31] Within the continental United States, primary Interstates – also called main line Interstates or two-digit Interstates – are assigned numbers less than 100.^[31]

In the numbering scheme, 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 (to avoid confusion with the U.S. Highways which increase from east to west and north to south), though there are exceptions to both principles in several locations. Numbers divisible by five are intended to be major arteries among the primary routes, carrying traffic long distances.^[6][32] Major north–south arterial Interstates increase in number from I-5 between Canada and Mexico along the West Coast to I-95 between Canada and Miami along the East Coast. Major west–east arterial Interstates increase in number from I-10 between Santa Monica, California and Jacksonville, Florida to I-90 between Seattle, Washington, and Boston, Massachusetts, with two exceptions. There is no Interstate 50 or Interstate 60, as routes with those numbers would likely pass through states which currently have U.S. Highways with the same numbers, which is not allowed under highway administration guidelines.^[31][33] Two-digit Interstates in Hawaii, as well as the "paper"^[34] Interstates of Alaska and Puerto Rico are numbered sequentially in order of funding without regard to the rules on odd and even numbers.

Several two-digit numbers are shared between two roads at opposite ends of the country (I-76, I-84, I-86, and I-88). Some of these were due to a change in the numbering system as a result of a new policy adopted in 1973. 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. The new policy stated, "No new divided numbers (such as I-35W and I-35E, etc.) shall be adopted." The new policy also recommended that existing divided numbers be eliminated as quickly as possible; however, an I-35W and I-35E still exist in the Dallas–Fort Worth metroplex in Texas, and an I-35W and I-35E that run through Minneapolis and Saint Paul, Minnesota still exist.^[31]

AASHTO policy allows dual numbering to provide continuity between major control points.^[31] This is referred to as a concurrency or overlap. For example, I-75 and I-85 share the same roadway in Atlanta; this 7.4-mile (11.9 km) section, called the Downtown Connector, is labeled both I-75 and I-85. Concurrencies between Interstate and U.S. Route numbers are also allowed in accordance with AASHTO policy, as long as the length of the concurrency is reasonable.^[31] In rare instances, two routes sharing the same roadway are signed as traveling in opposite directions; one such wrong-way concurrency is found between Wytheville and Fort Chiswell, Virginia, where I-81 north and I-77 south are equivalent (with that section of road traveling almost due east), as are I-81 south and I-77 north.

Auxiliary (three-digit) Interstates[link]

Auxiliary Interstate Highways are circumferential, radial, or spur highways that principally serve urban areas. These types of Interstate Highways are given three-digit route numbers, which consist of a single digit prefixed to the two-digit number of a nearby primary Interstate Highway. Spur routes deviate from their parent and do not return; these are given an odd first digit. Circumferential and radial loop routes return to Interstate Highways, and are given an even first digit. Due to the large number of these routes, auxiliary route numbers may be repeated in different states along the mainline.^[35] Some auxiliary highways do not follow these guidelines, however. See List of auxiliary Interstate Highways for examples.

Examples of the auxiliary Interstate Highway numbering system

In the example above, City A has an even-numbered circumferential highway. City B has an even-numbered circumferential beltway and an odd-numbered spur. City C has an even-numbered circumferential highway and an odd numbered spur. Because cities A, B, and C are in the same state, each auxiliary route carries a distinct three-digit route number.^[35]

Unlike primary Interstates, three-digit Interstates are signed as either west/east or north/south, depending on the general orientation of the route, without regard to the route number. For some looped Interstate routes, inner/outer directions are used as a directional labeling system, as opposed to compass directions.

Mile Markers and Exit Numbers[link]

On one or two digit Interstates, the mile marker numbering almost always begins at the south state line (for north-south Interstates) or the west state line (for east-west Interstates). If an Interstate originates within a state, the numbering begins from the location where the road begins in the south or west. Exceptions exist for Interstate Highways that used segments of roadway that were built prior to Interstate Highway standards being formalized and grandfathered into the system.

Three digit Interstates with an even first number that form a complete circumferential (circle) bypass around a city feature Mile Markers that are numbered in a clockwise direction, beginning just west of an Interstate that bisects the circumferential route near a south polar location. In other words, Mile Marker 1 on I-465, a 53-mile circumferential route around Indianapolis, is just west of its junction with I-65 on the south side of Indianapolis (on the South Leg of I-465), and Mile Marker 53 is just east of this same South Leg junction with I-65.

The exit numbers of interchanges are sequential, often linked to the mile markers so that the interchange exit number is the same as the number of the nearest mile marker.^[36]

Business routes[link]

AASHTO defines a category of special routes separate from primary and auxiliary Interstate designations. These routes do not have to comply to Interstate construction standards, but are routes that may be identified and approved by the association. The same route marking policy applies to both U.S. Numbered Highways and Interstate Highways; however, business route designations are sometimes used for Interstate Highways.^[37] Known as Business Loops and Business Spurs, these routes that principally travel through the corporate limits of a city, passing through the central business district of the city. Business routes are used when the regular route is directed around the city.^[37]

Alaska, Hawaii, and Puerto Rico[link]

Map of routes in Puerto Rico that receive funding from the Interstate program, but are not signed as Interstate Highways

The Interstate Highway System also extends to Alaska, Hawaii, and Puerto Rico, even though they have no direct land connections to any other states. However, their residents still pay federal fuel and tire taxes. Those Interstate Highways in Hawaii, all located on the most populous island of Oahu, carry the prefix H (e.g., Interstate H-1 and Interstate H-2). These expressways connect several military and naval bases together, as well as the important cities and towns spread across Oahu, and espcially the metropolis of Honolulu. Both Alaska and Puerto Rico have public highways that receive 90 percent of ther funding from the Interstate Highway program, although these highways have signs according to their local designations, but not their Interstate Highway numbers. These highways were neither planned according to nor constructed to the official Interstate Highway standards.^[38]

Financing[link]

I-787 in Watervliet, New York, showing the Exit 8 diamond interchange

About 70 percent of the construction and maintenance costs of Interstate Highways in the United States have been paid through user fees, primarily the fuel taxes collected by the federal, state, and local governments. To a much lesser extent they have been paid for by tolls collected on toll highways and bridges. The Highway Trust Fund, established by the Highway Revenue Act in 1956, prescribed a three-cent-per-gallon fuel tax, soon increased to 4.5 cents per gallon. In 1993, the tax was increased to 18.4 cents per gallon, where it remains as of 2012.^[39]

The rest of the costs of these highways are borne by general fund receipts, bond issues, designated property taxes, and other taxes. The federal contribution comes overwhelmingly from motor vehicle and fuel taxes (93.5 percent in 2007), and it makes up about 60 percent of the contributions by the states. However, any local government contributions are overwhelmingly from sources besides user fees.^[40] The portion of the user fees spent on highways themselves covers about 57 percent of their costs, with about one-sixth of the user fees being sent to other programs, including the mass transit systems in large cities. In the northeastern United States, some large sections of Interstate Highways that were planned or constructed before 1956 are still operated as toll roads. Others have had their construction bonds paid off and they have become toll-free, such as in Connecticut (I-95), Maryland (I-95), Virginia (I-95), and Kentucky (I-65).

As American suburbs have expanded, the costs incurred in maintaining freeway infrastructure have also grown, leaving little in the way of funds for new Interstate construction.^[41] This has led to the proliferation of toll roads (turnpikes) as the new method of building limited-access highways in suburban areas. Some Interstates are privately maintained (e.g., the VMS company maintains I-35 in Texas)^[42] to meet rising costs of maintenance and allow state departments of transportation to focus on serving the fastest-growing regions in their states.

Parts of the Interstate System might have to be tolled in the future to meet maintenance and expansion demands, as has been done with adding toll HOV/HOT lanes in cities such as San Diego, Salt Lake City, Minneapolis, Houston, Denver, Dallas, Atlanta, and close to Washington, D.C. (in Northern Virginia). Although part of the tolling is an effect of the SAFETEA-LU act, which has put an emphasis on toll roads as a means to reduce congestion.^[43][44] Present federal law does not allow for a state to change a freeway section to a tolled section for all traffic.^{[citation needed]}

Toll Interstate Highways[link]

An Interstate 376 trailblazer with the new black-on-yellow "Toll" sign.

Approximately 2,900 miles (4,700 km) of toll roads are included in the Interstate Highway System.^[45] While federal legislation initially banned the collection of tolls on Interstates, many of the toll roads on the system were either completed or under construction when the Interstate Highway System was established. Since these highways provided logical connections to other parts of the system, they were designated as Interstate highways. Congress also decided that it was too costly to either build toll-free Interstates parallel to these toll roads, or directly repay all the bondholders who financed these facilities and remove the tolls. Thus, these toll roads were "grandfathered" into the Interstate Highway System.^[46]

Toll facilities designated as Interstate highways (such as the Massachusetts Turnpike) were typically allowed to continue collecting tolls, but are generally ineligible to receive federal funds for maintenance and improvements. In addition, these toll facilities were grandfathered from Interstate Highway standards. A notable example is the western approach to the Benjamin Franklin Bridge in Philadelphia, where Interstate 676 has a surface street section through a historic area.

Policies on toll facilities and Interstate Highways have since changed. The Federal Highway Administration has allowed some states to collect tolls on existing Interstate Highways, while a recent extension of Interstate 376 included a section of Pennsylvania Route 60 that was tolled by the Pennsylvania Turnpike Commission before receiving Interstate designation. Also, newer toll facilities (like the tolled section of I-376, which was built in the early 1990s) must conform to Interstate standards. A new addition of the Manual on Uniform Traffic Control Devices in 2009 requires a black-on-yellow "Toll" sign to be placed above the Interstate trailblazer on Interstate Highways that collect tolls.^[47]

Legislation passed in 2005 known as SAFETEA-LU, encouraged states to construct new Interstate Highways through "innovative financing" methods. SAFETEA-LU facilitated states to pursue innovative financing by easing the restrictions on building interstates as toll roads, either through state agencies or through public–private partnerships. However, SAFETEA-LU left in place a prohibition of installing tolls on existing toll-free Interstates, and states wishing to toll such routes to finance upgrades and repairs must first seek approval from Congress.

Chargeable and non-chargeable Interstate routes[link]

Interstate Highways financed with federal funds are known as chargeable Interstate routes, and are considered part of the 42,000-mile (68,000 km) network of highways. Federal laws also allow non-chargeable Interstate routes, highways funded similarly to state and U.S. Highways to be signed as Interstates, if they both meet the Interstate Highway standards and are logical additions or connections to the system.^[48][49] These additions fall under two categories: routes that already meet Interstate standards, and routes not yet upgraded to Interstate standards. Only routes that meet Interstate standards may be signed as Interstates once their proposed number is approved.^[38]

Signage[link]

This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (June 2011)

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 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). There are, however, 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; placing exit number signage across the state was deemed too expensive. California began to incorporate exit numbers on its freeways in 2002 – Interstate, U.S., and state routes alike. Caltrans commonly installs exit number signage only when a freeway or interchange is built, reconstructed, retrofitted, or repaired to control costs. Most exits along California's Interstates now have exit number signage, particularly in rural areas.^{[citation needed]}

Exit numbers correspond to Interstate mileage markers in most states. On I-19 in Arizona, however, length is measured in kilometers instead of miles because, at the time of construction, a push for the United States to change to a metric system of measurement had gained enough traction that it was mistakenly assumed that all highway measurements would eventually be changed to metric; proximity to metric-using Mexico may also have been a factor, as I-19 indirectly connects I-10 to the Mexican Federal Highway system via surface streets in Nogales. Mileage count increases from west to east on most even-numbered Interstates; on odd-numbered Interstates mileage count increases from south to north. Some tollways, including the New York State Thruway and Jane Addams Memorial Tollway, use radial exit numbering schemes. Exits on the New York State Thruway count up from Yonkers traveling north, and then west from Albany. On the Jane Addams Memorial Tollway mileage markers count up from O'Hare International Airport traveling west, which is the starting point of the tollway.

As of November 2010 the Illinois State Tollway Authority has redone the mileage markers to be uniform with the rest of the state on I-90 (Jane Addams Memorial/Northwest Tollway) and the I-94 section of the Tri-State Tollway, which previously had matched the I-294 section starting in the south at I-80/I-94/IL Route 394. The tollway is also currently in the process of adding exit number tabs to the exits.^{[citation needed]}

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; as such, five of the main Interstate highways that remain completely within these states (87, 88, 89, 91, and 93) have interchanges numbered sequentially along their entire routes. Maine, Pennsylvania, Virginia, Georgia and Florida followed this system for a number of years, but since converted to mileage-based exit numbers. Georgia renumbered in 2000, while Maine did so in 2004. The Pennsylvania Turnpike uses both mile marker numbers and sequential numbers. Mile marker numbers are used for signage, while sequential numbers are used for numbering interchanges internally. The New Jersey Turnpike, including the portions which are signed as I-95 and I-78, also has sequential numbering, but other Interstates within New Jersey use mile markers.

I-87 in New York State is numbered in three sections. The first section is the portion of I-87 that makes up the Major Deegan Expressway, with interchanges numbered sequentially from 1 to 14. The second section of I-87 is a part of the New York State Thruway that starts in Yonkers (exit 1) and continues north to Albany (exit 24); at Albany, the Thruway turns west and becomes I-90 for exits 25–61. From Albany north to the Canadian border, the exits on I-87 are numbered sequentially from 1 to 44 along the New York State Northway. This often leads to confusion as there is more than one exit on I-87 with the same number. For example, exit 4 on Thruway section of I-87 connects with the Cross County Parkway in Yonkers, but exit 4 on the Northway is the exit for the Albany airport. These two exits share a number but are located 150 miles (240 km) apart.

There are four common signage methods on Interstates: One is locating a sign on the ground to the side of the highway, mostly the right, and is used to denote exits, as well as rest areas, motorist services such as gas and lodging, recreational sites, and freeway names. Another method is attaching the sign to an overpass. The two most common methods involve overhead gantries; they can be mounted either on half-gantries that are located on one side of the highway, like the ground-mounted sign; or full gantries that bridge the entire width of the highway and often show two or more signs.

Interstate shield[link]

Standard Interstate shields

Markers for Interstate 80 (left) and Business Loop Interstate 80 (right)

Interstate Highways are signed by a number placed on a trademarked^[50] red, white and blue sign. In the original design, the name of the state was displayed above the highway number, but in many states, this area is now left blank. The sign usually measures 36 inches (91 cm) high, and is 36 inches (91 cm) wide for two-digit Interstates or 45 inches (110 cm) for three-digit Interstates.^[51]

Interstate business loops and spurs use a special shield in which 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.^[51] The green shield is employed to mark the main route through a city's central business district, which intersects the associated Interstate highway at one (spur) or both (loop) ends of the business route. The route usually traverses the main thoroughfare(s) of the city's downtown area or other major business district.^[52] A city may have more than one Interstate-derived business route, depending on the number of Interstates passing through a city and the number of significant business districts therein.^[53]

Over time, the design of the Interstate shield has changed. In 1957, the Interstate shield designed by Texas Highway Department employee Richard Oliver was introduced, the winner of a contest which included 100 entries;^[54][55] at the time, the shield color was a dark navy blue and only 17 inches (43 cm) wide.^[56] The Manual on Uniform Traffic Control Devices (MUTCD) standards revised the shield in the 1961,^[57] 1971,^[58] and 1978^[59] editions.

Statistics[link]

Volume[link]

• Heaviest traveled: 374,000 vehicles per day: I-405 in Los Angeles, California (2008 estimate^[60]).

Elevation[link]

• Highest: 11,158 feet (3,401 m): I-70 in the Eisenhower Tunnel at the Continental Divide in the Colorado Rocky Mountains.^[61]
• Lowest (on land): −52 ft (−15.8 m): I-8 at the New River near Seeley, California.^[61]

Length[link]

• Longest: 3,020.54 miles (4,861.09 km): I-90 from Seattle, Washington, to Boston, Massachusetts.^[62][63]
• Longest (north–south): 1,920 mi (3,090 km): I-95 from the Canadian border to Miami, Florida, not counting the gap in New Jersey to be completed in 2017.^[62]
• Longest segment between state lines: 879 mi (1,415 km): I-10 in Texas from the New Mexico state line near El Paso to the Louisiana state line near Orange.^[64]
• Longest concurrency: 278.4 mi (448.0 km): I-80 and I-90; Gary, Indiana, to Elyria, Ohio.^[65]
• Shortest segment between state-lines: 453 ft (138 m): I-95 (Capital Beltway) on the Woodrow Wilson Bridge across the Potomac River where it briefly crosses the southernmost tip of the District of Columbia between its lines with Maryland and Virginia.^[63]
• Shortest (two-digit): 17.62 mi (28.36 km): I-97 from Annapolis to Baltimore, in Maryland.^[63]

States[link]

• Most states served by an Interstate: 15 states plus the District of Columbia: I-95 through Florida, Georgia, South Carolina, North Carolina, Virginia, DC, Maryland, Delaware, Pennsylvania, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire, and Maine.^[62]
• Most Interstates in a state: 29 routes: New York, totaling 1,674.73 mi (2,695.22 km).^[62]
• Most Interstate mileage in a state: 3,233.45 mi (5,203.73 km): Texas, in 17 different routes.^[62]

See also[link]

U.S. Roads portal

• Adopt a Highway
• Expressways of China
• Expressways in South Korea, signage and numbering heavily influenced by Interstate Highway System
• Highway patrol
• International E-road network (Europe)
• List of controlled access highway systems
• List of roads and highways
• Non-motorized access on freeways
• Transportation in the United States

Notes[link]

References[link]

Further reading[link]

External links[link]

Wikimedia Commons has media related to: Interstate Highway System

• Dwight D. Eisenhower National System of Interstate and Defense Highways, Federal Highway Administration (FHWA)
• Route Log and Finder List, FHWA
• Turner-Fairbank Highway Research Center, FHWA
• Interstate Highway System, Dwight D. Eisenhower Presidential Library and Museum
• "Keep on Trucking?: Would you pay more in taxes to fix roads and rail?", NOW on PBS

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Prescott Bush
United States Senator from Connecticut
In office November 5, 1952 – January 2, 1963
Preceded by	William A. Purtell
Succeeded by	Abraham A. Ribicoff
Personal details
Born	Prescott Sheldon Bush (1895-05-15)May 15, 1895 Columbus, Ohio
Died	October 8, 1972(1972-10-08) (aged 77) New York City
Nationality	American
Political party	Republican
Spouse(s)	Dorothy Walker Bush
Children	Prescott Bush, Jr. George H.W. Bush Nancy Walker Bush Ellis Jonathan Bush William H.T. Bush
Alma mater	Yale University
Religion	Episcopal
Signature
Military service
Service/branch	United States Army
Unit	American Expeditionary Forces
Battles/wars	World War I

Prescott Sheldon Bush (May 15, 1895 – October 8, 1972) was a Wall Street executive banker and a United States Senator, representing Connecticut from 1952 until January 1963. He was the father of George H. W. Bush (41st President of the United States) and the grandfather of George W. Bush (43rd President of the United States) and Jeb Bush (43rd Governor of Florida).

Early life[link]

Bush was born in Columbus, Ohio, to Samuel Prescott Bush and Flora Sheldon Bush. Samuel Bush was a railroad executive, then a steel company president, and, during World War I, also a federal government official in charge of coordination and assistance to major weapons contractors.

Bush attended St. George's School in Newport, Rhode Island, from 1908 to 1913. In 1913, he enrolled at Yale University, where his grandfather James Smith Bush, class of 1844, and his uncle Robert E. Sheldon Jr., class of 1904, had matriculated. Three subsequent generations of the Bush family have been Yale alumni. Prescott Bush was admitted to the Zeta Psi fraternity and Skull and Bones secret society. George H. W. Bush and George W. Bush are also members of that society.

Prescott Bush was a cheerleader,^[1] played varsity golf, football, and baseball, and was president of the Yale Glee Club.

Military service[link]

After graduation, Bush served as a field artillery captain with the American Expeditionary Forces (1917–1919) during World War I. He received intelligence training at Verdun, France, and was briefly assigned to a staff of French officers. Alternating between intelligence and artillery, Bush came under fire in the Meuse-Argonne offensive.

Business career[link]

After his discharge in 1919, Prescott Bush went to work for the Simmons Hardware Company in St. Louis, Missouri.

The Bushes moved to Columbus, Ohio in 1923, where Prescott Bush briefly worked for the Hupp Products Company. In November 1923 he became president of sales for Stedman Products in South Braintree, Massachusetts. During this time, he lived in a Victorian home at 173 Adams Street in Milton, Massachusetts, where his son, George H.W. Bush, was born.

In 1924, Bush became vice-president of A. Harriman & Co. His father-in-law, George Herbert Walker also worked with the company, as did E. Roland Harriman and Knight Woolley, Bush's Yale classmates and fellow Bonesmen.

In 1925, Bush joined the United States Rubber Company of New York City as manager of the foreign division, and moved to Greenwich, Connecticut.

In 1931, Bush became a partner of Brown Brothers Harriman & Co., which was created through the 1931 merger of A. Harriman & Co with Brown Bros. & Co. (a merchant bank founded in Philadelphia, Pennsylvania, in 1818) and with Harriman Brothers & Co. (established in New York City in 1927).

Bush was an avid golfer, and in 1935 named head of the USGA.^[2]

From 1944 to 1956, Bush was a member of the Yale Corporation, the principal governing body of Yale University. Bush was on the board of directors of CBS, having been introduced to chairman William S. Paley around 1932 by his close friend and colleague William Averell Harriman, who became a major Democratic Party power-broker.

[edit] Union Banking Corporation

Bush was one of seven directors (including W. Averell Harriman) of the Union Banking Corporation, an investment bank that operated as a clearing house for many assets and enterprises held by German steel magnate Fritz Thyssen.^[3][4] In July 1942 the bank was suspected of holding gold on behalf of Nazi leaders.^[5] A subsequent government investigation disproved those allegations, but confirmed the Thyssens' control, and in October 1942 the United States seized the bank under the Trading with the Enemy Act and held the assets for the duration of World War II.^[3]

According to the journalist Joe Conason Bush's involvement with UBC was purely commercial and that he was not a Nazi sympathizer.^{[6][dead link]} The Anti-Defamation League^[7] and historian Herbert Parmet^[4] agreed with that assessment.

Political Life[link]

Bush was politically active on social issues. He was involved with the American Birth Control League as early as 1942, and served as the treasurer of the first national capital campaign of Planned Parenthood in 1947. Bush was also an early supporter of the United Negro College Fund, serving as chairman of the Connecticut branch in 1951.

Bush with President Dwight D. Eisenhower in the Oval Office.

From 1947 to 1950, he served as Connecticut Republican finance chairman, and was the Republican candidate for the United States Senate in 1950. A columnist in Boston said that Bush "is coming on to be known as President Truman's Harry Hopkins. Nobody knows Mr. Bush and he hasn't a Chinaman's chance."^[8] Bush's ties with Planned Parenthood also hurt him in heavily Catholic Connecticut, and were the basis of a last-minute campaign in churches by Bush's opponents; the family vigorously denied the connection, but Bush lost to Benton by only 1,000 votes.

Bush sought a rematch with Benton in 1952, but withdrew as the party turned to William Purtell. The death of Senator Brien McMahon later that year however created a vacancy and this time Republicans nominated Bush.^[9] Bush defeated the Democratic nominee, Abraham Ribicoff, and was elected to the Senate. A staunch supporter of President Dwight D. Eisenhower, Bush served until January 1963. He was reelected in 1956 with 55 percent of the vote over Democrat Thomas J. Dodd (later U.S. Senator from Connecticut and father of the recent U.S. Senator from Connecticut, Christopher J. Dodd), and decided not to run for another term in 1962. He was a key ally for the passage of Eisenhower's Interstate Highway System,^[10] and during his tenure supported the Polaris submarine project (which were built by Electric Boat Corporation in Groton, Connecticut), civil rights legislation, and the establishment of the Peace Corps.^[11]

On December 2, 1954, Bush was part of the large (67–22) majority to censure Wisconsin Republican Senator Joseph McCarthy, after McCarthy had taken on the U.S. Army and the Eisenhower administration. During the debate leading to the censure, Bush said that McCarthy has "caused dangerous divisions among the American people because of his attitude and the attitude he has encouraged among his followers: that there can be no honest differences of opinion with him. Either you must follow Senator McCarthy blindly, not daring to express any doubts or disagreements about any of his actions, or, in his eyes, you must be a Communist, a Communist sympathizer, or a fool who has been duped by the Communist line."^[12] Eisenhower later included Bush's name on an undated handwritten list of prospective candidates he favored for the 1960 GOP presidential nomination.

In terms of issues, Bush often agreed with New York Governor Nelson Rockefeller, but personally disliked and politically opposed him, despite the close relationship his father had with the Rockefeller family. During the 1964 election, Bush denounced Rockefeller for divorcing his first wife and marrying a woman about 20 years his junior with whom Rockefeller had been having an affair while married to his first wife.^[11]

Another of Senator Bush's major legislative interests was flood and hurricane protection. He drafted Public Law 71, the Bush Hurricane Survey Act, enabling Army engineers to develop a new program of community protection against tidal flooding.^[13][14]

Personal life[link]

The grave of Prescott Bush

Bush married Dorothy Walker on August 6, 1921, in Kennebunkport, Maine. They had five children: Prescott Bush, Jr. (August 10, 1922 – June 23, 2010),^[15][16][17] George H. W. Bush (b. 1924, named after Dorothy's father George Herbert Walker), Nancy Bush (b. 1926), Jonathan Bush (b. 1931), and William "Bucky" Bush (b. 1938).

Bush founded the Yale Glee Club Associates, an alumni group, in 1937. Following his father-in-law, he was a member of the United States Golf Association, serving successively as secretary, vice-president and president, 1928–1935. He was a multi-year club champion of the Round Hill Club in Greenwich, Connecticut, and was on the committee set up by New York City Mayor Robert F. Wagner, Jr. to help create the New York Mets.

Bush maintained homes in New York, Long Island, and Greenwich, Connecticut; the family compound at Kennebunkport, Maine; a 10,000 acre (40 km²) plantation in South Carolina; and a secluded island off the Connecticut coast, Fishers Island.

The headstone of Prescott Bush

He died in 1972 at age 77 and was interred at Putnam Cemetery in Greenwich, Connecticut.

Writings[link]

Bush's articles include:

• "Timely Monetary Policy," Banking, June 1955 and July 1955
• "To Preserve Peace Let's Show the Russians How Strong We Are!" Reader's Digest, July 1959
• "Politics Is Your Business," Chamber of Commerce, State of New York, Bulletin, May 1960

References[link]