Yellowstone National Park

Established in 1872 as the world's first national park, Yellowstone sits atop one of Earth's largest active supervolcanoes and contains over 10,000 geothermal features. Its Old Faithful geyser erupts approximately every 90 minutes, drawing 4.5 million visitors annually to Wyoming, Montana, and Idaho. This is slower than the average eruption interval for Steamboat Geyser, which erupts every 3 to 10 days.