This article is for quizzes on Thursday May 12th...

The Federal-Aid Highway Act of 1956, popularly known as the National Interstate and Defense Highways Act (Public Law 84-627), was enacted on June 29, 1956, when President Dwight D. Eisenhower signed the bill into law. With an original authorization of US$25 billion for the construction of 41,000 miles (66,000 km) of the Interstate Highway System supposedly over a 10-year period, it was the largest public works project in American history through that time.

The addition of the term "Defense" in the Act's title was for two reasons: First, some of the original cost was diverted from defense funds. Secondly, most US Air Force bases have a direct link to the system. The purpose was to provide access in order to defend them during an attack. All of these links were in the original plans, although some, such as Wright Patterson were not connected up in the 1950s, but only somewhat later.

The money for the Interstate Highway and Defense Highways was handled in a Highway Trust Fund that paid for 90 percent of highway construction costs with the states required to pay the remaining 10 percent. It was expected that the money would be generated through new taxes on fuel, automobiles, trucks, and tires. As a matter of practice, the federal portion of the cost of the Interstate Highway System has been paid for by taxes on gasoline and diesel fuel.

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