The Tri-State district was an historic lead-zinc mining district located in southwest Missouri, southeast Kansas and northeast Oklahoma. The district produced lead and zinc for over 100 years. Production began in the 1850s and 1860s in the Joplin - Granby area of Jasper and Newton counties of southwest Missouri and continued until the closure of the Picher, Oklahoma mines in 1967. The tri-state district includes three mining-related Superfund sites: the Tar Creek Superfund site in Oklahoma, and two others in Missouri and Kansas.
- ^ Brockie, Douglas C., et al., The Geology and Ore Deposits of the Tri-State District of Missouri, Kansas and Oklahoma, in Ridge, John D., Ore Deposits of the United States, 1933-1967; Vol 1, Ch. 20, pp. 400 - 430, 1968, American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
- ^ http://digital.library.okstate.edu/encyclopedia/entries/T/TR014.html TRI-STATE LEAD AND ZINC DISTRICT, Oklahoma Historical Society
Coordinates: 37°00′N 94°30′W / 37.0°N 94.5°W