History.com: How Interstate Highways Gutted Communities and Reinforced Segregation

America's interstate highway system cut through the heart of dozens of urban neighborhoods. Congress approved the Federal-Aid Highway Act of 1956, authorizing what was then the largest public works program in U.S. history. It promised to construct 41,000 miles of an interstate highway system that would criss-cross the nation, expanding America's roadways and connecting 42 state capital cities and 90 percent of American cities with populations over 50,000. Its goal was to eliminate unsafe roads, inefficient routes and traffic jams that impede fast and safe cross-country travel. The U.S. Department of Transportation estimated more than 475,000 households and more than a million people were displaced nationwide because of the federal roadway construction.