Iron Mountain is a city in and the county seat of Dickinson County, Michigan, United States. The population was 7,518 at the 2020 census, down from 7,624 at the 2010 census. Located in the Upper Peninsula of Michigan, Iron Mountain was named for the valuable iron ore found in the vicinity. Iron Mountain is the principal city of the Iron Mountain micropolitan area, which includes all of Dickinson County and Florence County, Wisconsin.