Highway 55 (MT 55) in the U.S. State of Montana is a route running in a northerly direction from an intersection with MT 41 about 4 miles (6.4 km) north of the small town of Silver Star. The highway extends approximately 13 miles (21 km) to an interchange with Interstate 90 (I-90) at the north edge of the town of Whitehall. The route traverses largely agricultural land in the Jefferson River valley.