1956-largest public works project in the United States history; Eisenhower signed the law, which built over 40,000 miles of highways in the United States at a cost of $25 billion and created the interstate highway system; ostensibly to create routes for moving military supplies and for emergency evacuation in case of nuclear attack. The highway system made coast-to-coast driving a more common occurrence, and car-oriented vacations became a reality. - The growth of interstate highways allowed for a demographic shift as people vacationed, visited, and moved to areas in the south and southwest—the Sunbelt, from Florida through the deep South, all the way through Texas, New Mexico, and Arizona.