On July 21, 2023, the United States Office of Management and Budget defined the 12-county Denver-Aurora-Greeley, CO Combined Statistical Area as comprising the ten-county Denver–Aurora–Centennial, CO

The City of Castle Pines is a home rule municipality located in Douglas County, Colorado, United States. The city population was 11,036 at the 2020 United States census. Castle Pines is a part of the