US 310 starts at a junction with
US 14,
US 16,
US 20, and Wyoming Highway 789 in Greybull as an
unsigned highway and is concurrent with all four routes. It becomes signed northwest of Greybull, where it departs from US 14, US 16, and US 20, and continues north through the desert, still concurrent with Wyoming Highway 789. Near the town of
Lovell, US 310 passes by Lovell Lakes before turning west through a brief stretch of farmland that extends into
Cowley. From Cowley, the highway runs west to
Deaver, then due north to
Frannie, where it straddles the boundary between
Big Horn County and
Park County. Just to the north of Frannie, US 310 bends slightly to the west, so that the road is actually inside Park County by about 400 feet before reaching the
Montana state line. At the state line, Wyoming Highway 789 ends and US 310 continues northwest into the desert. At the junction with
Montana Highway 72, US 310 turns north, passing through farmland and the towns of
Bridger and
Fromberg before running concurrently with
US 212. The highway enters the city of
Laurel, where US 212 continues onto
I-90 and US 310 ends at Main Street (
I-90 Business and former
US 10). ==History==