State Route 320 (SR 320) is a short north–south state highway in western Ohio, a U.S. state. The southern terminus of SR 320 is at U.S. Route 35 (US 35) approximately 3 miles (4.8 km) southeast of New Paris, 0.75 miles (1.21 km) south of US 35's eastern junction with Interstate 70 (I-70).