US Highway 127 (US 127) is a part of the United States Numbered Highway System that runs from Chattanooga, Tennessee, to the Lower Peninsula of Michigan. In Ohio, the highway runs 194.27 miles (312.65 km) from the Ohio River in Cincinnati to the Michigan state line north of West Unity. US 127 runs south to north in Ohio's westernmost counties along the border of Indiana. The highway is a main route connecting many small towns, including eight county seats. The highway was first designated in 1926. Its route ended in downtown Toledo before being realigned to its current route in 1930.

Interstate 75 (I-75) runs from Cincinnati to Toledo by way of Dayton in the US state of Ohio. The highway enters the state running concurrently with I-71 from Kentucky on the Brent Spence Bridge over the Ohio River and into the Bluegrass region. I-75 continues along the Mill Creek Expressway northward to the Butler County line just north of I-275. From there, the freeway runs into the Miami Valley and then passes through the Great Black Swamp before crossing into Michigan.