Ohio State Route 320 is a short north-south highway in Southwestern Ohio. This runs from New Paris to near New Westville. OH St Rt 320 passes through the following towns in Preble County. New Paris New Westville. OH St Rt 320 is not multi-plexed in Preble County. OH St Rt 320 crosses the following highways in Preble County. Ohio State Route 121, at New Paris. U.S. Rt. 40, near New Westville. Interstate 70, near New Westville. U.S. Rt. 35, near New Westville. U.S. Rt. 35, near New Westville.
