The Dwight D. Eisenhower National System of Interstate and Defense Highways has been called the greatest public works project in history. From the day President Eisenhower signed the Federal-Aid Highway Act of 1956, the Interstate System has been an integral part of American culture and way of life—from transportation in our daily lives to the impact of population centers. Every citizen has been touched by it, if not directly as motorists, than indirectly because every item we buy has been on the Interstate Highway System at some point. President Eisenhower considered it one of the most important achievements of his two terms in office, and historians agree.