Interstate 675 (I-675) is an auxiliary Interstate Highway in the suburbs of Dayton in the US state of Ohio. I-675 serves as an eastern bypass of Dayton that is 26.53 miles (42.70 km) long. As originally proposed, the route was to reconnect with I-75 north of Dayton near Northridge rather than going east toward Springfield and I-70. Construction was completed in 1987, though some have lobbied to extend the highway west of Dayton.

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.