U.S. Route 24 in Ohio

Part of the US 24 freeway in Ohio

From the Indiana state line easterly to Baltimore Street at the border of unincorporated Defiance Township and the city of Defiance, US 24 is an expressway which mostly has interchanges but features intersections with select county and township roads. From Baltimore Street to State Route 281 (SR 281) at the border of Defiance and unincorporated Noble Township, US 24 is a freeway. From SR 281 to US 6 west in Henry County's Napoleon Township, US 24 is once again an expressway. From US 6 west to Interstate 475 (I-475) in the city of Maumee, US 24 is a freeway. The route continues northeasterly as a surface street through downtown Maumee and the western side of Toledo, where it turns into Telegraph Road and stays on it past the Michigan state line. The route then continues northerly into Michigan as a north–south highway.

The original route of US 24 closely followed the Maumee River from the Indiana state line to downtown Toledo. Much of the original route has been given county road designations, often as County Route 424. A portion of the old route that was bypassed between Defiance and Napoleon between 1964 and 1969 was designated SR 424 until 2012. The original route through Toledo followed North River Road, transitioning into Broadway and Summit streets, before turning northwesterly along Jefferson Avenue, to Collingwood Boulevard, continuing northward to Detroit Avenue via a short connection on Cherry Street. The route along Detroit Avenue from Cherry Street to Telegraph Road, and Telegraph into Michigan, has always been part of US 24 since its designation. As the Anthony Wayne Trail was completed from the south side into downtown, US 24 was shifted onto the new route, feeding into a one-way pair along Erie and Michigan streets to Monroe Street, before returning to Collingwood and its original alignment. Portions of these routes were at times concurrent with portions of US 23 and US 25.

The concurrent segment with US 25 between Conant Street/US 20 and the intersection of Anthony Wayne Trail and Detroit Street (crossing over the Ohio Turnpike) became a concurrency with SR 25 following US 25's decommissioning in Ohio and Michigan in 1973, as SR 25 replaced US 25 along Detroit Avenue to the Cherry Street/US 24 intersection. The former concurrency along Detroit Avenue to Telegraph Road became just US 24, while the northernmost section of Detroit Avenue reverted to local control.[2][3] The route of US 24 in the Toledo–Maumee area would remain unchanged until 1986, when the Ohio Department of Transportation switched the US 24 and SR 25 designations, placing US 24 on Detroit Avenue and rerouting SR 25 to continue northeasterly from Monroe Street via the Erie/Michigan one-way couplet to the Greenbelt Parkway and a new terminus at I-280.[4]

Upgrades to the route around Napoleon began in 2008. This included the construction of a new route from east of Napoleon to north of Waterville, bypassing the original routing of the highway. This rerouting was done to "alleviate safety concerns caused by the mixture of truck traffic and residential travel" along US 24's former routing.[5] New alignments west of Defiance through to I-469 in Fort Wayne, Indiana, were also built in the late 2000s.[6] The conversion to an expressway, first proposed in 1969, was done due to the high number of road accidents along the old alignment, which comprised only two lanes and was frequently used by tractor-trailers.[7]

• U.S. Route 24 Realignment/Expansion ODOT website