Aspen is the home rule city that is the county seat of, and the most populous municipality in, Pitkin County, Colorado, United States. The city population was 7,004 at the 2020 United States census. Aspen is in a remote area of the Rocky Mountains' Sawatch Range and Elk Mountains, along the Roaring Fork River at an elevation just below 8,000 feet (2,400 m) on the Western Slope, 11 miles (18 km) west of the Continental Divide. Aspen is now a part of the Rifle, CO Micropolitan Statistical Area.