Ohio State Route 191 is a fairly short route running north-south in eastern Williams County. Williams County, for context, is the northwestern corner of Ohio. The southern end is at US Route 6 just north of Evansport. From there, Ohio Route 191 runs north, picking up Ohio Route 2 at a junction where it crosses Ohio Route 34. At Stryker, Ohio Route 191 sends Ohio Route 2 to continue easterly. Beyond the town of Stryker, Ohio Route 191 continues another 7 miles to West Unity, where it ends at US Route 20A. This piece of US Route 20A also carries an otherwise northbound US Route 127 that is temporarily jogging toward the east.