How many people live in Douglas County, CO?
Updated Apr. 6, 2026Refreshed annually
In 2024, there were about 394,000 people living in Douglas County, CO. That makes Douglas County the sixth-most populous county in Colorado. It is home to 6.6% of people living in the state.
394K
population of Douglas County, CO (2024)
6.6%
County share of the Colorado population (2024)
About 394,000 people lived in Douglas County, CO in 2024.
Population estimates, 2000–2024
What are Douglas County, CO’s age demographics?
About 58,900 Douglas County, CO residents are aged 65 and older in 2024. That represents 14.9% of its population. For comparison, the age group represents 16.5% of Colorado’s population and 18% in the US overall.
Another 87,800 Douglas County residents, or 22.3% of the population, were children under 18. For comparison, the age group represents 20.5% of Colorado’s population and 21.6% in the US overall.
A lower share of Douglas County, CO's population is aged 65 or older than the US as a whole.
Population estimates by age group, (2024)
What are Douglas County, CO’s racial and ethnic demographics?
Non-Hispanic white residents make up 77.3% of the Douglas County, CO population, higher than the national share of 57.5%. Douglas County, CO also has a larger share of people identifying as non-Hispanic Asian (7%) than the US overall (6.5%).
In contrast, Douglas County’s non-Hispanic Black or African American population accounts for 1.9%, below the 12.6% nationwide, and the Hispanic population makes up 10.7% of the county, compared with 20% nationally.
Racial and ethnic make up differ based on location. These figures reflect how people identified their race alone (not in combination with other races), and separate out Hispanic or Latino ethnicity, following Census reporting standards.
Douglas County, CO has a higher share of a non-Hispanic white population than Colorado as a whole.
Population estimates by race and ethnicity, (2024)
The largest city or town in Douglas County, CO is Castle Rock with about 83,200 residents in 2024.
Cities and towns in Douglas County, CO ranked by population
Population (2024), includes only portions within county
| City or town | Population | |
|---|---|---|
| 1. | Castle Rock | 83,213 |
| 2. | Parker | 65,473 |
| 3. | Castle Pines | 15,162 |
| 4. | Lone Tree | 14,061 |
| 5. | Aurora (pt.) | 4,169 |
| 6. | Littleton (pt.) | 630 |
| 7. | Larkspur | 223 |
| 8. | Balance of Douglas County | 211,064 |
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Methodology
USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.
The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.
Page sources
USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.
