All the sections lie along the Little Missouri River between Medora and Watford City. The South Unit, just north of Medora, comprises a petrified forest, Wind Canyon, and eroded badlands. Theodore Roosevelt's Elkhorn Ranch, 35 miles (56 km) north-northwest of Medora, includes the site where his cabin once stood. The North Unit is a scenic badlands area 12 miles (19 km) south of Watford City. Cottonwood, elm, and ash trees thrive in the area, which is inhabited by bison, deer, elk, prairie dogs, and dozens of species of birds.

Roosevelt first visited the area in 1883, when the frontier was fast disappearing. That same year he joined with several men as partners in an open-range cattle ranch, the Maltese Cross Ranch, in what is now the South Unit of the park. In 1884 he established his own cattle ranch, the Elkhorn. The harsh winter of 1886–87 nearly wiped out his investment, but he continued to visit the Elkhorn Ranch from time to time until 1896. Roosevelt's experiences in this part of the West were the inspiration for several of his books and influenced his conservationist policies later, when he was president.