List of Interstate Highways in Ohio

There are a total of 21 Interstate Highways in Ohio, including both primary and auxiliary routes. With the exception of the Ohio Turnpike (which carries portions of Interstate 76 (I-76), I-80, and I-90), all of the Interstate Highways are owned and maintained by the U.S. state of Ohio through the Ohio Department of Transportation (ODOT); 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 1572.35 mi. Ohio has more route miles than this, most of which comes from I-80 running concurrently with I-90 for 142.80 mi. The Interstate Highways in Ohio range in length from I-71, at 248.15 mi, all the way down to I-471, at 0.73 mi.

As of 2019, out of all the states, Ohio has the fifth-largest Interstate Highway System. Ohio also has the fifth-largest traffic volume and the third-largest quantity of truck traffic. Ohio ranks second in the nation in terms of the number of bridges for its Interstates.

History
On June 29, 1956, President Dwight D. Eisenhower signed the Federal Aid Highway Act of 1956, which called for the construction of up to 41000 mi of Interstate Highways. Of that, up to 1500 mi were to be built in Ohio. The same year, Ohio passed a law which raised the state's speed limit to 60 mph, and in 1957, Ohio began the construction of its Interstate Highway allotment. By 1958, Ohio had spent more money on its Interstate Highways than either New York or California. Ohio had completed the construction of 522 mi of pavement by 1960, 684 mi by 1962, and 1000 mi by 1970. By the end of 1971, Ohio had only 167 mi of Interstate still to build. On September 19, 2003, Ohio finally finished the originally planned Interstate Highway System.