High Quality Content by WIKIPEDIA articles! State Route 300 (SR 300, OH 300) is a 6.33-mile (10.19 km) long north–south state highway in northwestern Ohio, a U.S. state. The southern terminus of SR 300 is at a T-intersection with U.S. Route 6 (US 6) approximately 1.50 miles (2.41 km) west of the village of Helena. Its northern terminus is at US 20 just over 2.50 miles (4.02 km) southeast of Woodville.