At one time Plains served as a wintering point for Indians and their horses, under the name Horse Plains. Stockmen began driving their horses to the area from as far as Walla Walla, Washington. When many of the ranges were covered with snow, wild horses would gather in this open, protected pasture. The post office opened in 1883. The name Horse Plains was later shortened to Plains.
Elevation: 2,468 feet
Plains is located in northwestern Montana, northwest from Missoula on MT Highway 200 and approximately 25 miles northeast of St. Regis.