Devils Tower became the first U.S. national monument when President Theodore Roosevelt proclaimed it in 1906.
Roosevelt issued the proclamation under the Antiquities Act of 1906, which authorized presidents to protect federal lands containing historic landmarks, prehistoric structures, and objects of scientific interest. Devils Tower, a striking rock formation in northeastern Wyoming, was the first site selected under that new authority.
The formation rises about 867 feet above the surrounding Belle Fourche River landscape. Geologists generally describe it as an igneous intrusion, although the exact process that shaped its distinctive columns remains debated. Its vertical joints create the famous polygonal appearance.
Devils Tower also has deep cultural importance for several Indigenous nations, including the Lakota, Cheyenne, and Kiowa. The name “Devils Tower” reflects a historical translation and naming dispute, while many Indigenous communities use names connected with bears or other traditional stories. National monument status differs from national park status, though both can protect important landscapes.