June 29, 1956 The Federal Aid Highway Act is Signed into law

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 Dwight D. Eisenhower signed the bill into law. With an original authorization of 25 billion dollars 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.[1]

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.

http://en.wikipedia.org/wiki/Federal-Aid_Highway_Act_of_1956