The City and County of Denver (pronounced /ˈdɛnvər/) is the capital and the most populous city of the U.S. state of Colorado. Denver is a consolidated city-county, located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains. The Denver downtown district is located immediately east of the confluence of Cherry Creek with the South Platte River, approximately 12.3 miles (20 km) east of the foothills of the Rocky Mountains. Denver is nicknamed the "Mile-High City" because its official elevation is exactly one mile (1.6 km) or 5,280 feet (1,609.344 m) above sea level. The 105th meridian west of Greenwich passes through Union Station and is the temporal reference for the Mountain Time Zone.
The population of Denver was 600,158 according to the 2010 census. According to 2009 Census estimates, Denver was the 26th most populous U.S. city. The 10-county Denver-Aurora-Broomfield, CO Metropolitan Statistical Area had an estimated 2009 population of 2,552,195 and ranked as the 21st most populous U.S. metropolitan statistical area and the 12-county Denver-Aurora-Boulder Combined Statistical Area had an estimated 2009 population of 3,110,436 and ranked as the 16th most populous U.S. metropolitan area. Denver is the most populous city within a 500-mile (800 km) radius and the second-largest city in the Mountain West and Southwest after Phoenix. Denver is the most populous city in the Front Range Urban Corridor, an urban region stretching across 18 counties in two states, and the second-largest in area after Colorado Springs. The population of the Front Range Urban Corridor was estimated to be 4,328,406 in 2009.