The Dwight D. Eisenhower National System of Interstate an Defense Highways, commonly called the Interstate Highway System (or simply, the Interstate System), is a network of highways (also called freeways or expressways) in the United States that is named for the president who was in office and championed its creation. The Interstate Highway System is a separate system within the larger National Highway System. The entire system, as of 2004, had 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.