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 60s 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.[1][2] The tri-state district includes three Superfund sites: the Tar Creek Superfund site in Oklahoma, and two others in Missouri and Kansas.