acquired after the National Steel Corporation bankruptcy. U.S. Steel acquired National Steel Corporation in May 2003 for $850 million and assumption of $200 million in debt. U.S. Steel operates Great Lakes Works in Ecorse, Michigan, Midwest Plant in Portage, Indiana, and Granite City Steel in Granite City, Illinois. In 2008 a major expansion of Granite City was announced, including a new coke plant with an annual capacity of 650,000 tons. U.S. Steel operates Fairfield Works in Fairfield, Alabama (Birmingham), employing 1,500 people, and operates a sheet galvanizing operation at the Fairless Works facility in Fairless Hills, Pennsylvania, employing 75 people. U.S. Steel operates three pipe mills: Fairfield Tubular Operations in Fairfield, Alabama (Birmingham), McKeesport Tubular Operations, in McKeesport, Pennsylvania, and Texas Operations (Formerly Lone Star Steel) in Lone Star, Texas. A fourth pipe mill, Lorain Tubular Operations in Lorain, Ohio is no longer operating at this time. U.S. Steel operates two major taconite mining and pelletizing operations in northeastern Minnesota's Iron Range under the operating name Minnesota Ore Operations. The Minntac mine is located near Mountain Iron, Minnesota, and the Keetac mine is near Keewatin, Minnesota. U.S. Steel announced on February 1, 2008, that it would be investing approximately $300 million in upgrading (project later abandoned) the operations at Keetac, a facility purchased in 2003 from the now-defunct National Steel Corporation. In December 2022, an investment of $150 million was made in the plant. U.S. Steel has completely closed nine of its major integrated mills. The Duluth Works in Duluth, Minnesota, closed in 1973. The Ohio Works and Macdonald Works in Youngstown, Ohio, closed in 1980, the Duquesne Works in Duquesne, Pennsylvania, and Ensley Works in Ensley, Alabama in 1984, the Homestead Works in Homestead, Pennsylvania, in 1986. Geneva Steel in Vineyard, Utah, was sold in 1987, South Chicago's South Works closed in 1992, followed by the National Tube Works in Mckeesport, Pennsylvania, in 2014. Internationally, U.S. Steel operates facilities in Slovakia (former East Slovakian Iron Works in Košice). It also operated facilities in Serbia – former Sartid with facilities in Smederevo (steel plant, hot and cold mill) and Šabac (tin mill). U.S. Steel added facilities in Texas with the purchase of Lone Star Steel Company in 2007. The company operates two joint ventures in Pittsburg, California, with POSCO of South Korea. U.S. Steel added facilities in Hamilton and Nanticoke, Ontario, Canada, with the purchase of Stelco (now U.S. Steel