Figure 16. Peabody’s 75 Million Ton Per-Year North Antelope Rochelle Mine, which began operation in 1983, is America’s largest coal mine. It is located in southeast Campbell County, Wyoming, in the Powder River Basin. The coal is sub-bituminous, with 8,800 BTU/lb. Sulfur is 0.23%; moisture is 28%, and ash is 4.6%. The seam is 65 feet thick, and recoverable reserves are estimated to be 1,375 million tons.