The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly called the Interstate Highway System (or simply, the Interstate System), is a network of limited-access highways (also called freeways or expressways) in the United States that is named for the President who championed its creation. The Interstate Highway System is a subsystem of the National Highway System. The entire system, as of 2004, has a total length of 46,837 miles (75,376 km), making it both the largest highway system in the world and the largest public works project in history.
While Interstate Highways usually receive substantial federal funding (90% federal and 10% state), and they comply with federal standards, they are owned, built, and operated by the states or toll authorities. For example, the original Woodrow Wilson Bridge (part of Interstate 95 and Interstate 495), was maintained by the federal government; its new span is now jointly owned and maintained by the state of Maryland and the Commonwealth of Virginia. There are also other Interstate Highways within the District of Columbia, which is federal territory.
This expressway system serves nearly all major U.S. cities, with many Interstates passing through downtown areas. The distribution of virtually all goods and services involves Interstate Highways at some point. Residents of American cities commonly use urban Interstates to travel to their places of work. The vast majority of long-distance travel, whether for vacation or business, uses the national road network; of these trips, about one-third (by the total number of miles driven in the country in 2003) utilize the Interstate system.