Annual visitors: 607,418
South Dakota’s Mt. Rushmore is a more famous, and visited, NPS property. But Wind Cave, also located in the state, is worth a visit, too. It’s one of the oldest National Parks, established in 1903 by President Teddy Roosevelt, and only about an hour’s drive from Mt. Rushmore.
As you may have guessed, Wind Cave is named after its principal attraction, an enormous, underground cave. It sits below the South Dakota prairie, and runs for at least 147 miles, making it one of the longest caves in the world. Wind Cave is particularly notable for the unusual calcite formations within it, called boxwork.
Why is it called Wind Cave? Because, like all caves, it seeks to balance the pressure inside the cave with the barometric pressure outside, creating a passage of wind that can feel like the cave is breathing.