County Maps US

Arapahoe County, Colorado

A county in Colorado, ranked 3 of 64 by population.

CountyFIPS 08005

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

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Population
673,820
+18,551 (+2.8%) since 2020
Land area
797.9
square miles. A further 0.9% of the total area is water
Population density
845
people per square mile, computed rather than published
County seat
Littleton
Seat of county government.
Established
1861
164 years ago
Largest city
Aurora city
Population 344,658 for the whole place, which extends beyond this county.

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 Arapahoe 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 Arapahoe 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 260 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 Arapahoe 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
Population673,8203rd of 64105th of 3,144
Land area797.9 sq mi48th of 641,071st of 3,144
Population density845 per sq mi3rd of 64186th of 3,144
Median household income$101,08711th of 64162nd of 3,143

Full data for Arapahoe County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population673,820Vintage 2025 Population Estimates
Population in 2020655,269Vintage 2025 Population Estimates
2020 estimates base?655,085Vintage 2025 Population Estimates
Land area797.9 sq mi2025 Gazetteer Files
Water area7.6 sq mi2025 Gazetteer Files
Total area805.5 sq mi2025 Gazetteer Files
Population density?845 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$101,087American Community Survey 2020-2024 5-Year Estimates
Median home value$561,200American Community Survey 2020-2024 5-Year Estimates
Median age37.3American Community Survey 2020-2024 5-Year Estimates
Households257,232American Community Survey 2020-2024 5-Year Estimates
Housing units269,345American 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
+3,332
8,005 births, 4,673 deaths
Net migration
-5,238
More people moved out than moved in.

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

The 7 areas bordering Arapahoe 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
Adams CountyColorado63 mi554,668
Denver CountyColorado57 mi740,613
Elbert CountyColorado51 mi30,534
Douglas CountyColorado21 mi399,396
Washington CountyColorado12 mi4,732
Jefferson CountyColorado4.5 mi580,451
Lincoln CountyColorado0.4 mi5,645

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.