High Quality Content by WIKIPEDIA articles! There are a total of 21 Interstate Highways in Ohio, including both primary and auxiliary routes. All of the Interstates are owned and maintained by the state of Ohio; however, they were all built with money from the U.S. federal government. The road miles of these 21 Interstates add up to a total of 1,572.35 miles (2,530.45 km). Ohio has more route miles than this, most of which comes from Interstate 80 being concurrent with Interstate 90 for 142.80 miles (229.81 km). The Interstate Highways in Ohio range in length from Interstate 90, at 244.75 miles (393.89 km), all the way down to Interstate 471, at 0.73 miles (1.17 km).