Interstate 75 (I-75) runs from Cincinnati to Toledo by way of Dayton in the U.S. 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 north into the Miami Valley and then passes through the Great Black Swamp before crossing into Michigan.

In Cincinnati, approximately 17 miles (27 km) of the highway will be totally reconfigured by three separate ODOT projects happening simultaneously. The Brent Spence Bridge Corridor project will replace the Brent Spence Bridge and continue north to the Western Hills Viaduct. The Mill Creek Expressway project will modernize the Mill Creek Expressway segment of the highway, from the Western Hills Viaduct to Ronald Reagan Highway interchange. The Thru the Valley project will continue from the Reagan Highway north to Interstate 275. These projects will improve safety by eliminating all left-hand exit ramps and increasing vehicular capacity.

The segment from West Chester to Middletown was widened in 2010. Construction on the highway continues from Middletown all the way to I-675.

In Dayton, Interstate 75 is currently in the process of total reconfiguration with several projects occurring simutaneously. The intersection of I-75 and I-70 was reconfigured to handle an increased traffic load at the intersection. I-75 through downtown Dayton at the intersections of Ohio State Route 4, US 35, and between are currently under construction for widening and modernization.

Between I-475 in Perrysburg and State Route 15 in Findlay, Interstate 75 is only two lanes wide in each direction, and extremely congested, due to carrying traffic headed towards Dayton via I-75, and Columbus via State Route 15 and US 23. However, there are no plans in the immediate future to widen this stretch of road. A few miles later, Interstate 75 intersects with I-80/I-90 the Ohio Turnpike. After the interchange, Interstate 75 continues north into Downtown Toledo. Just north of Downtown Toledo, Interstate 475 rejoins with Interstate 75. After continuing northeast, Interstate 75 intersects Interstate 280 (Ohio), which takes you back to I-80/I-90 the Ohio Turnpike. Following this, Interstate 75 enters Michigan and follows the shore of Lake Erie.