The first numbered routes in Delaware came in 1925 with the creation of the U.S. Highway System, in which US 13, US 40, and US 113 were made by law to run through the state. In 1930 and again in 1932, the Delaware State Highway Department suggested giving numbers to state roads to go along with the existing U.S. Highway System. By 1936, Delaware began giving numbers to state routes. In 1956, the Interstate Highway System was made, with under 40 miles of Interstate highway made by law in New Castle County.