State Route 307 (SR 307) is an east–west state highway in the northeastern portion of the U.S. state of Ohio. Its western terminus is at State Route 528 on the southern boundary of Madison, and its eastern terminus is at State Route 193 nearly 7 miles (11 km) southeast of Jefferson.SR 307 was commissioned in the mid-1930s and the route was swapped with another state route one year later. The route was extended in the later 1930s, to an intersection with SR 84.