Ohio State Route 660
State Route 660 is an east-west state highway in the east-central portion of Ohio. Existing entirely within Guernsey County, the western terminus of State Route 660 is at State Route 313 just east of the hamlet of Claysville. Its eastern terminus is at a signalized T-intersection with State Route 209 near Cambridge Municipal Airport, south of the city limits of Cambridge, as well as State Route 209's interchange off of Interstate 70.