List of numbered highways in Ohio

Standard Highway markers for Ohio
US 6 at State Route 174 in Willoughby Hills, Lake County
Highway names
Interstates:	Interstate nn (I-nn)
US Highways:	U.S. Route nn (US nn)
State:	State Route nn (SR nn)
System links
Ohio Highways Interstate U.S. State Former Scenic

The Ohio Department of Transportation (ODOT) is responsible for the establishment and classification of a state highway network which includes interstate highways, U.S. highways, and state routes. As with other states, U.S. and Interstate highways are classified as state routes in Ohio. There are no state routes which duplicate an existing U.S. or Interstate highway in Ohio.

Ohio distinguishes between "state routes", which are all the routes on ODOT's system, and "state highways", which are the roads on the state route system which ODOT maintains, i.e. those outside municipalities, with a special provision for Interstate Highways. Besides the state highway network, there are various county and township road networks within the state.