The Metro-Denver area consists of eleven counties.

The City and County of Denver 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 eighteen 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.

Adams County – Adams County is the fifth most populous of the 64 counties of the state of Colorado of the United States. The United States Census Bureau estimates that the county population was 430,826 in 2008, a 23.87% increase since U.S. Census 2000. Adams County is named for Alva Adams, Governor of the State of Colorado 1887-1889, 1897-1899, and 1905. The county seat is Brighton. Adams County is part of the Denver-Aurora-Broomfield, CO Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area.

Arapahoe County is the third most populous of the 64 counties of the state of Colorado of the United States. The United States Census Bureau estimated that the county population was 544,282 in 2008, a 10.09% increase since U.S. Census 2000. The county seat is Littleton; the most populous city is Aurora. Arapahoe County is part of the Denver-Aurora Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area. Arapahoe County calls itself “Colorado’s First County” since its origins predate the Pike’s Peak Gold Rush.

The City and County of Broomfield is a prominent suburb and tier of the Denver metropolitan area in the State of Colorado of the United States. Broomfield has a consolidated city and county government which operates under Article XX, Sections 10-13 of the Constitution of the State of Colorado. The United States Census Bureau records stated that the population was 55,889 on April 1, 2010. Broomfield is the 16th most populous city and the 16th most populous county in Colorado. Broomfield is a part of the Denver-Aurora-Broomfield, CO Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area.

Clear Creek County is one of the 64 counties of the state of Colorado of the United States. The county population was 9,322 at U.S. Census 2000. The county seat is Georgetown. Despite its location in the Rocky Mountains, Clear Creek County is part of the Denver-Aurora Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area.

Douglas County is the eighth most populous of the 64 counties of the state of Colorado, in the United States. The county is located midway between Colorado’s two largest cities: Denver and Colorado Springs. The United States Census Bureau estimates that the county population was 280,621 in 2008, a 59.7% increase since the 2000 United States Census, making Douglas County one of the fastest growing counties in the United States. Douglas County is part of the Denver-Aurora Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area. The county seat is Castle Rock, named after a prominent castle tower-shaped butte just north of the town.

Douglas County is lightly wooded, mostly with ponderosa pine, with broken terrain characterized by mesas and small streams. Cherry Creek and Plum Creek rise in Douglas County and flow north toward Denver and into the South Platte River. Both were subject to flash flooding in the past, Plum Creek being partially responsible for the Denver flood of 1965. Cherry Creek is now dammed.

Most residents commute to workplaces elsewhere in the metropolitan area outside of the county. Suburban development is displacing the ranching economy of the county

Elbert County is the 21st most populous of the 64 counties of the State of Colorado of the United States. The county population was 19,872 at U.S. Census 2000. The county seat is Kiowa. Despite its location on the eastern plains, Elbert County is part of the Denver-Aurora Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area.

Gilpin County is the second least extensive of the 64 counties of the State of Colorado of the United States. Gilpin County was named after Colonel William Gilpin, the first Governor of the Territory of Colorado. The county population was 4,757 at U.S. Census 2000. The county seat is Central City. Despite its location in the Rocky Mountains, Gilpin County is part of the Denver-Aurora Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area. Gilpin County was formed in 1861, at the time of Colorado statehood.

Jefferson County is the fourth most populous of the 64 counties of the State of Colorado of the United States. The United States Census Bureau estimates that the county population was 533,339 in 2008. The county seat is Golden and the most populous city is Lakewood. Jefferson County is part of the Denver-Aurora Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area. The center of population of the State of Colorado is located in Jefferson County.

Located along the Front Range of the Rocky Mountains, Jefferson County is part of the Denver metropolitan area. The major expressway Interstate 70 traverses Jefferson County from east-to-west, passing just south of the county seat of Golden. Jefferson County is a quite long county from north to south, following the Front Range. The county is known as the Gateway to the Rocky Mountains.

A major employer in Jefferson County is the large Coors Brewing Company in Golden. Also, the state-supported Colorado School of Mines is located in Jefferson County, offering programs in mining and engineering.

Jefferson County is commonly nicknamed Jeffco. The name Jeffco is incorporated in the name of the Jeffco School District, the Jeffco Business Center Metropolitan District No. 1, and several businesses located in Jefferson County. Jeffco is also incorporated in the unofficial monikers of many Jefferson County agencies. The Rocky Mountain Metropolitan Airport operated by Jefferson County was previously known as the Jeffco Airport.

Park County is the 17th most extensive of the 64 counties of the State of Colorado of the United States. The county was named after the large geographic region known as South Park, which was named by early fur traders and trappers in the area. The geographic center of the State of Colorado is located in Park County. The county population was 14,523 at U.S. Census 2000. The county seat is Fairplay. Despite its location in the heart of the Rocky Mountains, Park County is part of the Denver-Aurora Metropolitan Statistical Area and the Denver-Aurora-Boulder Combined Statistical Area.