Sixteen mines in the Powder River Basin produce 43% of coal
Most of the coal produced in the PRB supports electric power generation in the United States. Starting in the 1990s, many coalfired power plants switched to subbituminous coal from the PRB—which has relatively low sulfur content—to meet tightening Clean Air Act emission 2003, the Powder River Basin yielded more coal than the Appalachian coal basins in the eastern United States.