Arch Coal, Inc. (Arch)is the coal producer. During the year ended December 31, 2012, it sold approximately 140.8 million tons of coal, including approximately 4.3 million tons of coal it purchased from third parties, representing roughly 14% of the 2012 United States coal supply. As of December 31, 2012, it operated, or contracted out the operation of, 32 active mines located in each of the coal-producing regions of the United States.The Company's operating segments are the Powder River Basis (PRB) segment, with operations in Wyoming; the Western Bituminous (WBIT) segment, with operations in Utah and Colorado; the Appalachia (APP) segment, with operations in West Virginia, Kentucky, Maryland and Virginia; and its Illinois segment, which includes its operations in Illinois. Geology, coal transportation routes to consumers, regulatory environments and coal can vary from segment to segment.