The Ohio Department of Transportation is the administrative department of the Ohio state government responsible for developing and maintaining all state and U.S. roadways outside of municipalities and all Interstates except the Ohio Turnpike. In addition to highways, the department also helps develop public transportation and public aviation programs. ODOT is headquartered in Columbus, Ohio. Formerly, under the direction of Michael Massa, ODOT initiated a series of interstate-based Travel Information Centers, which were later transferred to local sectors. The Director of Transportation is part of the Governor's Cabinet.

State Route 4, formerly known as Inter-county Highway 4 until 1921 and State Highway 4 in 1922, is a major north–south state highway in Ohio. It is the fifth longest state route in Ohio. Its southern terminus is at U.S. Route 42 in Cincinnati, Ohio, and its northern terminus is at U.S. Route 6 in Sandusky, Ohio. Its path is nearly ruler-straight for many miles. Some portions of the route are still marked as Dixie Highway. The northern portion was constructed by the Columbus and Sandusky Turnpike Company, see Turnpike Lands.