Ohio State Route 174 is a short north-south route in the eastern reaches of the Cleveland metropolitan area. It stems southerly from Willoughby, to end after nine miles of travel in Gates Mills, Ohio. Ohio Route 174 follows along the Chagrin River Valley for its entire length. The northern end in Willoughby is at US Route 20, just south of that highway's junction with Ohio Route 640. The southern end crosses US Route 322 before ending in Gates Mills. The southern end is not at a numbered highway, but at a local road named Old Mill Road.