IRON MOUNTAIN, a city and the county-seat of Dickinson county, Michigan, U.S.A., about 50 m. W. by N. of Escanaba, in the S.W. part of the Upper Peninsula. Pop. (1900) 9242, of whom 4376 were foreign-born; (1904) 8585; (1910) 9216. It is served by the Chicago & North Western and the Chicago, Milwaukee & Saint Paul railways. The city is situated about 1160 ft. above sea-level in an iron-mining district, and the mining of iron ore (especially at the Great Chapin Iron Mine) is its principal industry. Iron Mountain was settled in 1879, and was chartered in 1889.