Douglas County, Colorado

Douglas County
One of two county buildings for Douglas County in Castle Rock
Location within the U.S. state of Colorado
Colorado's location within the U.S.
Coordinates: 39°21′N 104°56′W / 39.35°N 104.93°W / 39.35; -104.93
Country United States
State Colorado
FoundedNovember 1, 1861
Named afterStephen A. Douglas
SeatCastle Rock
Largest communityHighlands Ranch
Area
  Total
843 sq mi (2,180 km2)
  Land840 sq mi (2,200 km2)
  Water2.6 sq mi (7 km2)  0.3%
Population
 (2020)
  Total
357,978
  Estimate 
(2024)
393,995
  Density420/sq mi (160/km2)
Time zoneUTC−7 (Mountain)
  Summer (DST)UTC−6 (MDT)
Congressional districts4th, 6th
Websitewww.douglas.co.us

Douglas County is a county located in the U.S. state of Colorado. As of the 2020 Census, the population was 357,978. The county is named in honor of U.S. Senator Stephen A. Douglas. The county seat is Castle Rock.

Douglas County is part of the Denver metropolitan area. It is located midway between Colorado's two largest cities, Denver and Colorado Springs, and contains a portion of Aurora, the state's third-largest city. Douglas County has the highest median household income of any Colorado county or statistical equivalent. It is ranked seventh nationally in that category.