define interstate highway system
Interstate Highway System. 1. a network of U.S. highways connecting the 48 contiguous states and most of the cities with populations above 50,000, begun in the 1950s and estimated to carry about a fifth of the nation's traffic. Examples from the Web for Interstate Highway System Expand. Contemporary Examples. And in the 20th century, the federal government built the Interstate Highway System, without which, say, Walmart, could not exist. Eisenhower and Congress worked to enact the Interstate Highway System.