How the Interstate Highway System was built

According to the Federal Highway Administration, the Dwight D. Eisenhower System of Interstate and Defense Highways was developed through decades of federal legislation and state cooperation. Congress established the legal and financial framework for the network, which connects metropolitan areas and industrial centers across the United States.

Early road programs and planning

The federal role in roadbuilding began in 1893 when the Department of Agriculture established the Office of Road Inquiry to collect information, the Federal Highway Administration states. To instruct local builders on construction methods, the federal government constructed early demonstration routes called object-lesson roads, starting in Atlanta, Georgia, in 1895. In 1916, President Woodrow Wilson signed the Federal Aid Road Act, creating a partnership between federal and state officials to improve rural roads.

Before the federal interstate system, roads like the Lincoln Highway connected the country from coast to coast. Between 1922 and 1923, federal funds supported a model section of the Lincoln Highway in Indiana that was designed to accommodate future traffic needs. In 1919, the U.S. Army conducted a transcontinental motor convoy from Washington, D.C., to San Francisco to test wartime mobility, an experience that convinced participant Dwight D. Eisenhower of the need for better two-lane highways.

The first interstate designations

Formal planning for a modern network started in the late 1930s. The Federal-Aid Highway Act of 1938 directed the Bureau of Public Roads to study a toll-financed superhighway system. The bureau determined a toll network would not be self-supporting and instead recommended a 26,700-mile interregional highway network.

In 1941, President Franklin D. Roosevelt appointed a committee to evaluate the need for a national expressway system. The committee released a report in January 1944 supporting a 33,900-mile system alongside 5,000 miles of auxiliary urban routes. Acting on these recommendations, Congress passed the Federal-Aid Highway Act of 1944, authorizing the designation of up to 40,000 miles of interstate highways.

The 1944 act specified the routes should connect principal metropolitan areas, serve national defense, and link suitable border points in Canada and Mexico, the Federal Highway Administration says. On Aug. 2, 1947, federal officials announced the selection of the first 37,700 miles of routes, which were proposed by state highway agencies and reviewed by the Department of Defense. However, construction progressed slowly because early legislation did not authorize dedicated funds for the system.

The 1956 Highway Act and funding

In January 1955, President Eisenhower met with an advisory committee led by General Lucius Clay to discuss financing plans for the highway program. Although Congress did not adopt the committee’s specific plan, a revised funding mechanism was resolved with the Federal-Aid Highway Act of 1956. President Eisenhower signed the act on June 29, 1956, authorizing an expanded 41,000-mile system and establishing nationwide design standards.

The 1956 legislation set the federal government share of project costs at 90 percent. Title II of the act created the Highway Trust Fund to finance the construction on a pay-as-you-go basis without contributing to the federal budget deficit. Revenue from federal gas taxes and other motor-vehicle user taxes was credited to this fund to cover the federal share of the highway projects.

On Oct. 22, 1956, John A. Volpe took the oath of office as the first Federal Highway Administrator. The Federal Highway Administration notes this was the only time a president attended the swearing-in of an administrator for the agency.

Cost estimates and system additions

Following the 1956 act, Secretary of Commerce Sinclair Weeks announced the designation of 2,102 miles of new interstate routes on Oct. 18, 1957. According to the Federal Highway Administration, the secretary selected these additions based on national defense, system integration, industry transportation requirements, and population.

To distribute funds among the states, Congress required the federal government to periodically estimate the cost of completing each state’s portion of the system. Between 1958 and 1991, 15 estimates were submitted to Congress to serve as the basis for funding apportionments. The final estimate in January 1991 placed the total cost to complete the system at approximately $128.9 billion, with a federal share of $114.3 billion.

Congress continued to expand the authorized size of the system in the decades following its creation. The Federal-Aid Highway Act of 1968 authorized an additional 1,500 miles, raising the statutory ceiling to 42,500 miles. By December 1997, the Federal Highway Administration reports that more than 2,108 miles had been added to the system across 30 states without federal interstate construction funding.