Devils Tower was the first national monument designated in the United States.
President Theodore Roosevelt proclaimed Devils Tower National Monument in Wyoming on September 24, 1906. The proclamation used authority from the Antiquities Act, signed earlier that year, which allowed presidents to protect historic landmarks, structures, and objects of scientific interest on federal land.
Devils Tower is a striking geological formation rising about 867 feet above the surrounding terrain. It is especially notable for its columnar-jointed phonolite porphyry, whose vertical columns create the monument’s distinctive appearance.
The site has long-standing cultural importance for Indigenous peoples, and several tribes maintain traditional associations with the formation. The name “Devils Tower” reflects an old translation history, while many Indigenous communities use other names. The monument is not the same thing as a national park; national monuments can be designated by presidential proclamation.