Black Hills National Forest is located in southwestern South Dakota and northeastern Wyoming. The forest has an area of over 1.25 million acres (5,066 km²) and is managed by the Forest Service. Forest headquarters are located in Custer, South Dakota. There are local ranger district offices in Custer, Rapid City, and Spearfish in South Dakota, and in Sundance, Wyoming.Predominantly ponderosa pine, the forest also includes hard woods like aspen, bur oak, and birch. The lower elevations include grassland prairie, but the National Forest System lands encompass most of the mountainous region known as the Black Hills of South Dakota and Wyoming. Within the forest is Harney Peak which is the tallest mountain in South Dakota and the highest peak east of the Rocky Mountains in the United States.