State Route 15 (SR 15) is a north–south and east–west route in northwestern Ohio. Its southern (eastern) terminus is at its interchange with U.S. Route 23/State Route 103 (US 23/SR 103) near Carey, and its northern (western) terminus is at the Michigan state line north of Pioneer, where the route continues in Michigan as M-99. The route is signed east–west from Carey to Bryan, and it is signed north–south from there to the Michigan state line.
SR 15 is an expressway for its southernmost 19 miles (31 km): two miles (3.2 km) where it runs concurrently with Interstate 75 (I-75), three miles (4.8 km) where it runs concurrently with US 68, and the final 14 miles (23 km) as a stand-alone limited-access road until its junction with US 23. The final 17 miles (27 km) are part of a heavily traveled[citation needed] corridor providing the most direct route between Detroit, Toledo, Findlay, Marion and Columbus.
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