The Tri-State district was an historic lead

Lead

Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

-zinc

Zinc

Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

 mining

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 district located in southwest Missouri

Missouri

Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...

, southeast Kansas

Kansas

Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...

 and northeast Oklahoma

Oklahoma

Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...

. The district produced lead and zinc for over 100 years. Production began in the 1850s and 60s in the Joplin

Joplin, Missouri

Joplin is a city in southern Jasper County and northern Newton County in the southwestern corner of the US state of Missouri. Joplin is the largest city in Jasper County, though it is not the county seat. As of the 2010 census, the city population was 50,150...

 - Granby

Granby, Missouri

Granby is a city in Newton County, Missouri, United States. The population was 2,134 at the 2010 census. It is part of the Joplin, Missouri Metropolitan Statistical Area.-Geography:Granby is located at ....

 area of Jasper

Jasper County, Missouri

Jasper County is a county located in the US state of Missouri. It is included in the Joplin, Missouri Metropolitan Statistical Area. The 2010 total population of Jasper County was 117,404. It is the ninth most populous county in Missouri. Its county seat is Carthage, making it one of the few...

 and Newton counties of southwest Missouri and continued until the closure of the Picher, Oklahoma

Picher, Oklahoma

Picher is a ghost town and former city in Ottawa County, Oklahoma, United States. Formerly a major national center of lead and zinc mining at the heart of the Tri-State Mining District, over a century of unrestricted subsurface excavation dangerously undermined most of Picher's town buildings and...

 mines in 1967. The tri-state district includes three Superfund

Superfund

Superfund is the common name for the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 , a United States federal law designed to clean up sites contaminated with hazardous substances...

 sites: the Tar Creek Superfund site

Tar Creek Superfund site

Tar Creek Superfund site is a United States Superfund site located in Picher and Cardin, Oklahoma. Chat piles left behind by the mining companies contain lead dust that has blown around the city. Elevated lead levels in Picher children have led to learning disabilities and other problems...

in Oklahoma, and two others in Missouri and Kansas.