Dirt Road Through Grasslands Near Sheep Mountain, Badlands National Park

Badlands National Park's south unit is laced with unpaved roads like this one, which wind through mixed-grass prairie between the park's eroded buttes. The park covers roughly 244,000 acres and was established in 1978, though the striated hills visible along routes near Sheep Mountain have been taking shape for nearly half a million years as wind and water strip away layers of Oligocene-era sediment. This part of the park overlaps the Pine Ridge Reservation and is co-managed with the Oglala Sioux Tribe, whose ancestral homeland extends across the surrounding grasslands. Bighorn sheep and bison range through this section of prairie, and black-footed ferrets were reintroduced to the area in the 1990s after the species was once thought extinct in the wild.