US 30 heads east across northern Ohio via Mansfield and Canton. After several upgrades, it is now a four-lane divided highway from the Indiana state line to Canton with controlled-access freeway sections between Van Wert and Delphos, Bucyrus and Mansfield, and Massillon and Canton. At Upper Sandusky, the highway runs concurrent with US 23. There is no direct interchange between US 30 and Interstate 75 where the roads cross in Beaverdam.

US 30 in Ohio has received upgrades continually since the 1950s. As of 2012[update], the Ohio Department of Transportation is studying one portion not upgraded, from SR 44 to SR 11, with plans to create a toll highway along the corridor.

From 1932 to 1974, US 30 split into US 30N and US 30S within Ohio. US 30S became Ohio State Route 309 and US 30N became the current US 30 mainline.

US 30 in Ohio generally follows the route of the Lincoln Highway.

List of unused highways in Ohio