The highway's southern terminus, just north of Bozeman Hot Springs and about 7 miles (11 km) west of Bozeman, is a census-designated place (CDP) known as "Four Corners."

From Four Corners, U.S. Route 191 (US 191) runs east to Bozeman, and south to West Yellowstone; MT 84 travels west to Norris; and MT 85 runs north to Belgrade.

The designated MT 85 terminates near the southern end of Belgrade, at an interchange with Interstate 90 (I-90).

Once it reaches Belgrade, it expands to a four-lane road with a center turning lane.

The road continues north as Jackrabbit Lane, its street name in Belgrade.