South Park is a grassland flat within the basin formed by the Rocky Mountains' Mosquito and Park Mountain Ranges within central Colorado. This high valley ranges in elevation from approximately 9,000 to 10,000 ft (3,000 m). It encompasses approximately 1,000 square miles (2,590 km² or 640,000 acres) around the headwaters of the South Platte River in Park County approximately 60 mi (100 km) southwest of Denver. It is the largest and southernmost of three similarly named high altitude basins in the Front Range of Colorado, the others being North Park and Middle Park. The largest town in the basin is Fairplay, with a population of 681.