Arch Coal, Inc. (Arch) is a coal producer. During the year ended December 31, 2011, the Company sold approximately 156.9 million tons of coal, including approximately 5.5 million tons of coal it purchased from third parties, representing roughly 14% of the United States coal supply. It sells its coal to power plants, steel mills and industrial facilities. As of December 31, 2011, it operated, or contracted out the operation of, 46 active mines located in coal-producing regions of the United States. The Company operates in three business segments: the Powder River Basis (PRB) segment, with operations in Wyoming; the Western Bituminous (WBIT) segment, with operations in Utah, Colorado and southern Wyoming; the Appalachia (APP) segment, with operations in West Virginia, Kentucky, Maryland and Virginia; and its Other segment, which includes its operations in Illinois. On June 15, 2011, the Company acquired International Coal Group, Inc.