Divide was named because it is near the Continental Divide. This is where waters on the west side end up in the Pacific Ocean and streams from the east slope drain toward the Gulf. The Union Pacific station served as a stock shipping and distribution point for the Big Hole Valley. The first post office was established in 1873 with Charles Wunderlich as postmaster.
Divide is located in southwestern Montana, southwest of Butte, at the junctions of I-15 and Montana Highway 43.