Elkhorn Ranch State Historic Site, Ranch historic site in Billings County, North Dakota, United States

Elkhorn Ranch is a historic site in Billings County, North Dakota, on the west bank of the Little Missouri River about 35 miles north of Medora. Cottonwood trees line the river; the surrounding land is rolling prairie and badlands. Only foundation stones and depressions mark the ranch buildings Theodore Roosevelt had built in 1884.

Roosevelt founded the ranch in 1884 as his Dakota residence, bringing skilled workers from Maine to construct the buildings. This move marked his embrace of western life and the beginning of his years as a working rancher.

The site preserves the Maltese Cross Cabin, a log cabin Roosevelt used at his first ranch south of Medora before moving to the Elkhorn in 1884. The cabin was later shown at the 1904 St. Louis World's Fair and now stands at the state historic site in Medora.

The site is reached by a maintained gravel road from Medora and has interpretive signs explaining the ranch layout. Sturdy shoes are recommended since the ground is uneven and can become slippery after rain.

In 1886 Roosevelt tracked a boat thief who had stolen his boat from the Elkhorn Ranch, caught him near the Montana border, and made him walk to Dickinson for trial. The episode became known as the "Three Bears" incident, after the boat's name.