<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> The Dwight D. Eisenhower National System of Interstate and Defense Highways (commonly known as the Interstate Highway System, Interstate Freeways, or simply the Interstate) is a network of controlled - access highways that forms a part of the National Highway System of the United States . The system is named for President Dwight D. Eisenhower, who championed its formation . Construction was authorized by the Federal Aid Highway Act of 1956, and the original portion was completed 35 years later, although some urban routes were cancelled and never built . The network has since been extended and, as of 2013, it had a total length of 47,856 miles (77,017 km). As of 2013, about one - quarter of all vehicle miles driven in the country use the Interstate system . In 2006, the cost of construction was estimated at about $425 billion (equivalent to $526 billion in 2016). </P> <Table> <Tr> <Td> </Td> <Td> Remarks in Cadillac Square, Detroit President Eisenhower delivered remarks about the need for a new highway program at Cadillac Square in Detroit on October 29, 1954 Text of speech excerpt </Td> </Tr> <Tr> <Td_colspan="2"> Problems playing this file? See media help . </Td> </Tr> </Table>

How many miles of interstate highways are there in the us