Great Sand Dunes National Park, in southern Colorado, has the highest sand dunes in North America. Some of these dunes are 750 feet (230 meters) tall. The dunes were deposited over thousands of years by southwesterly winds rising against the Sangre de Cristo Mountains.
The U.S. Congress established Great Sand Dunes National Monument in 1932. In 2000, Congress upgraded the area to a national park. The change in status became official in 2004, after purchases of additional land had been completed. The legislation of 2000 also created the Great Sand Dunes National Preserve, adjoining the national park. The preserve includes alpine forests, lakes, and wetlands. For the current areas of the park and preserve, see National Park System (table: National monuments) ; National Park System (table: National preserves) .
