Great Sand Dunes National Park

Location: Colorado

Year Established: 2004

Area: 42,983.74 acres (173.9 km2)

Annual Visitors: 271,774

The tallest sand dunes in North America, up to 750 feet (230 m) tall, were formed by deposits of the ancient Rio Grande in the San Luis Valley. Abutting a variety of grasslands, shrublands, and wetlands, the park also has alpine lakes, six 13,000-foot mountains, and old-growth forests.