State Route 677 (SR 677) is a nearly 5-mile-long (8.0 km) north–south running state route existing entirely in Vinton County, Ohio.

Its southern terminus is at US 50, slightly to the east of McArthur in Elk Township, and its northern terminus is at SR 278 in Zaleski.

The route passes through rural east-central Vinton County while connecting the two towns.

Locally, the route is known as Powder Plant Road, as an Austin Powder Company explosives plant lies along the route.

[3][4] The entire route is in Vinton County.