The Thunder Basin National Grassland is located in northeastern Wyoming in the Powder River Basin between the Big Horn Mountains and the Black Hills. The Grassland ranges in elevation from 3,600 to 5,200 feet, and the climate is semi-arid. The Grassland provides opportunities for recreation, including hiking, sightseeing, hunting, and fishing. There are no developed campgrounds; however, camping is allowed. Land patterns are very complex because of the intermingled federal, state, and private lands.

The Powder River Basin is a geologic structural basin in southeast Montana and northeast Wyoming, about 120 miles (190 km) east to west and 200 miles (320 km) north to south, known for its extensive coal reserves. The former hunting grounds of the Oglala Lakota, the area is very sparsely populated and is known for its rolling grasslands and semiarid climate.