Black Thunder Coal Mine is located in Wyoming

The Black Thunder Coal Mine is a surface coal mine in the U.S. state of Wyoming, located in the Powder River Basin which contains one of the largest deposits of coal in the world. Black Thunder is the second most productive mine in the United States, providing the U.S. with eight percent of its coal supply. In 2007, the mine produced 86,196,275 short tons (78.2 million metric tonnes) of coal,^[2] nearly 20 percent of Wyoming's total coal production, and higher than 23 other individual coal producing states.^[2]

• http://en.wikipedia.org/wiki/Black Thunder Coal Mine