Known as Fish Lake Valley Road, the highway was a part of former SR 3A.

SR 773 begins at a junction with State Route 264 north of Fish Lake Valley.

The route follows Fish Lake Valley Road northeast to its terminus at U.S. Route 6 (US 6), about 6 miles (9.7 km) west of Coaldale.

The highway originally composed the northern 10 miles (16 km) of State Route 3A, a route christened in 1933 to connect State Route 15 (now US 6) to Fish Lake Valley and Dyer.

The entire route is in Esmeralda County.