• The finalized route and roadway numbering plan, approved and adopted on 14 August 1957.

  • A 1947 Public Roads Administration map of the National System of Interstate Highways. Maps like these were used to inform Senators and Congressional Representatives where the proposed routes crossed their districts, in the hopes of winning political and financial support for their construction.

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National Highway System

Despite pressure from the Army, the War Department, and some in Congress, support for such a costly public works project remained low. Desire for an interstate highway system stalled completely during the Great Depression and the Second World War. Almost 20 years after the creation of the Pershing Map, President Franklin D. Roosevelt established the National Interregional Highway Committee to investigate the viability of an interstate road network. Its 1944 report refined Pershing’s concept and emphasized transcontinental, long-haul roads. But it wasn’t until the post-World War II era—when the automobile and the open road became fixtures of the middle class and symbols of the American Dream—that a plan for what would become the Interstate and Defense Highway System (IDHS) was drafted. When now-President Eisenhower signed the Federal Highway Act of 1956 into law, authorizing 41,000 miles of interstate, it was as much on behalf of an eager motoring public as the Army. The first mile of asphalt was laid the very same year, and construction of the entire system was to be complete in two decades. This projection was optimistic; the network was not considered finished until 1991.