County Maps US

Adams County, Colorado

A county in Colorado, ranked 5 of 64 by population.

CountyFIPS 08001

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

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Population
554,668
+34,257 (+6.6%) since 2020
Land area
1,167
square miles. A further 1.4% of the total area is water
Population density
475
people per square mile, computed rather than published
County seat
Brighton
Seat of county government.
Established
1901
124 years ago
Largest city
Thornton city
Population 147,766 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 Adams 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 Adams 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 268 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 Adams 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
Population554,6685th of 64132nd of 3,144
Land area1,167 sq mi39th of 64527th of 3,144
Population density475 per sq mi5th of 64291st of 3,144
Median household income$94,57117th of 64230th of 3,143

Full data for Adams County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population554,668Vintage 2025 Population Estimates
Population in 2020520,411Vintage 2025 Population Estimates
2020 estimates base?519,580Vintage 2025 Population Estimates
Land area1,167 sq mi2025 Gazetteer Files
Water area16.8 sq mi2025 Gazetteer Files
Total area1,184 sq mi2025 Gazetteer Files
Population density?475 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$94,571American Community Survey 2020-2024 5-Year Estimates
Median home value$484,200American Community Survey 2020-2024 5-Year Estimates
Median age34.8American Community Survey 2020-2024 5-Year Estimates
Households188,730American Community Survey 2020-2024 5-Year Estimates
Housing units195,793American 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
+3,356
6,730 births, 3,374 deaths
Net migration
+1,976
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 7 areas bordering Adams 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
Denver CountyColorado72 mi740,613
Arapahoe CountyColorado63 mi673,820
Weld CountyColorado43 mi378,426
Morgan CountyColorado24 mi30,306
Washington CountyColorado18 mi4,732
Broomfield CountyColorado16 mi79,174
Jefferson CountyColorado8.5 mi580,451

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.