Elkhorn Ranch, Historical ranch in Billings County, US.

Elkhorn Ranch is a former ranch site in Billings County, North Dakota, on the banks of the Little Missouri River 35 miles north of Medora. Theodore Roosevelt's log ranch house, built by Bill Sewall and Wilmot Dow in the winter of 1884–1885, was gone by 1901; only its foundation remains. The site is now a unit of Theodore Roosevelt National Park.

Theodore Roosevelt established the ranch in 1884 as a cattle operation while living in the Dakota Territory. His time here influenced his later conservation efforts and shaped his views on land preservation.

The name comes from the elk that Roosevelt and his men hunted in the area. Visitors today can follow the Maah Daah Hey Trail, which links the site to the park's two other sections, and see Roosevelt's writing desk from the ranch displayed in the national park.

The site lies 35 miles north of Medora, North Dakota, on the banks of the Little Missouri River, and is reached by unpaved roads; no guided tours are offered. The ranch house itself is gone, leaving only its foundation, so plan for rough road conditions and extra travel time.

In spring 1886 thieves stole Roosevelt's boat from the Elkhorn Ranch. He, Bill Sewall and Wilmot Dow built a raft, caught the three men downriver, and Roosevelt held them at shotgun point on the march to Dickinson, North Dakota, where he collected a $50 reward.