Iron Mountain is an unincorporated community in southwestern St. Francois County, Missouri, United States. It is located about six miles south of Bismarck. The community was founded in 1836 as a mining site and it was named for nearby Iron Mountain, once thought to be made completely of iron ore.
The railroad history of the area runs deep, as the railways were key to the distribution of the minerals being mined. The Iron Mountain and Southern Railway was prominent during the development of the Iron Mountain community in the 19th century.