Mammoth, Montana

Mammoth is an unincorporated community and census-designated place (CDP) in Madison County, Montana, United States. It is in the northern part of the county, in the valley of the South Boulder River within the northern end of the Tobacco Root Mountains. Via the South Boulder River, it is part of the Jefferson River watershed, one of the headwaters of the Missouri River.

Mammoth is reached by South Boulder Road, which leads north 11 mi to Montana Highway 359 at a point 5 mi south of Cardwell.

Mammoth was first listed as a CDP prior to the 2020 census, when it had a population of 4.