Federal-Aid Highway Act of 1956
1956 U.S. legislation creating the Interstate Highway System
What was Federal-Aid Highway Act of 1956?
The Federal-Aid Highway Act of 1956, also known as the National Interstate and Defense Highways Act, Pub. L. 84–627 was enacted on June 29, 1956, when President Dwight D. Eisenhower signed the bill into law. With an original authorization of $25 billion (equivalent to $220 billion in 2025) for the construction of 41,000 miles (66,000 km) of the Interstate Highway System 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 because some of the original cost was diverted from defense funds and "because of [the Interstate Highway System']s primary importance to the national defense".
Background and consequences
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.