The Interstate Highway System was authorized by the Federal-Aid Highway Act of 1956 popularly known as the National Interstate and Defense Highways Act of 1956 on June 29. It had been lobbied for by major U.S. automobile manufacturers and championed by President Dwight D. Eisenhower, who was influenced by his experiences in 1919 as a young soldier crossing the country (following the route of the Lincoln Highway) and his appreciation of the German autobahn network as a necessary component of a national defense system.[7] In addition to facilitating private and commercial transportation, it would provide key ground transport routes for military supplies and troop deployments in an emergency.
Initial federal planning for a nationwide highway system began in 1921, when the Bureau of Public Roads asked the Army to provide a list of roads it considered necessary for national defense. This resulted in the Pershing Map.[8] Later that decade, highways such as the New York parkway system were built as part of local or state highway systems. As automobile traffic increased, planners saw a need for such an interconnected national system to supplement the existing, largely non-freeway, United States Numbered Highway system. By the late 1930s, planning had expanded to a system of new superhighways. In 1938, President Franklin D. Roosevelt gave BPR chief Thomas MacDonald a hand-drawn map of the U.S. marked with eight superhighway corridors for study.[8] The publication General Location of National System of Interstate Highways maps out what became the Interstate System, and is informally known as the Yellow Book.[9]