Massive machinery is at work in the open-pit Wyodak coal mine in the coal-rich Powder River Basin outside Gillette, Wyoming. The operation utilizes a truck and shovel mining method to produce low-sulfur, sub-bituminous coal for domestic energy generation. The mine ships its coal to the adjacent Wyodak power plant and to other customers via railroad. Wyodak Resources Development, a subsidiary of the Black Hills Corporation, operates the mine. Photo by Carol Highsmith.