State Route 191 (abbreviated as SR 191) is a north–south state highway in northwestern Ohio, a U.S. state. State Route 191's southern terminus is at U.S. Route 6 approximately 4 miles (6.4 km) south of Stryker. Its northern terminus is at the concurrency of U.S. Route 20A and U.S. Route 127 in downtown West Unity. Between its southern terminus and Stryker, State Route 191 runs parallel to, and to the east of, the Tiffin River.