County Maps US

Douglas County, Colorado

A county in Colorado, ranked 6 of 64 by population.

CountyFIPS 08035

Within Colorado
Douglas County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Castle Rock, the county seat, located via the 2025 Census Gazetteer.

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Population
399,396
+39,081 (+10.8%) since 2020
Land area
840.9
square miles. A further 0.3% of the total area is water
Population density
475
people per square mile, computed rather than published
County seat
Castle Rock
Seat of county government.
Established
1861
164 years ago
Largest city
Castle Rock town
Population 83,815.

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

Satellite view

Aerial imagery of Douglas County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.

Aerial view of Douglas County, Colorado from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 800 by 688 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

Where Douglas County ranks

Position among the 64 counties of Colorado, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn ColoradoNationally
Population399,3966th of 64195th of 3,144
Land area840.9 sq mi47th of 64992nd of 3,144
Population density475 per sq mi5th of 64291st of 3,144
Median household income$149,5941st of 646th of 3,143

Full data for Douglas County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population399,396Vintage 2025 Population Estimates
Population in 2020360,315Vintage 2025 Population Estimates
2020 estimates base?357,993Vintage 2025 Population Estimates
Land area840.9 sq mi2025 Gazetteer Files
Water area2.6 sq mi2025 Gazetteer Files
Total area843.5 sq mi2025 Gazetteer Files
Population density?475 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$149,594American Community Survey 2020-2024 5-Year Estimates
Median home value$713,600American Community Survey 2020-2024 5-Year Estimates
Median age39.6American Community Survey 2020-2024 5-Year Estimates
Households139,960American Community Survey 2020-2024 5-Year Estimates
Housing units144,432American Community Survey 2020-2024 5-Year Estimates

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.

How the population changed

The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:

Births minus deaths
+2,065
4,121 births, 2,056 deaths
Net migration
+4,265
More people moved in than moved out.

Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.

The 5 areas bordering Douglas County

Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.

Bordering areaStateShared borderPopulation
Jefferson CountyColorado46 mi580,451
Elbert CountyColorado30 mi30,534
Arapahoe CountyColorado21 mi673,820
El Paso CountyColorado20 mi757,040
Teller CountyColorado16 mi24,756

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

Side by side

All 64 counties of Colorado

Open the interactive Colorado county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.