Wind Cave National Park. South Dakota.
Wind Cave National Park is in the southwestern corner of South Dakota. It's known for the vast, underground Wind Cave, with chambers like the Post Office and the Elks Room. Many of the cave’s walls are rich in honeycomb-shaped calcite formations known as boxwork. The park's prairie and pine forests are home to bison, elk and pronghorn antelopes. Trails include Rankin Ridge, with views of the Black Hills.
Established: January 9, 1903