County Maps US

Colusa County, California

A county in California, ranked 50 of 58 by population.

CountyFIPS 06011

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

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Population
21,836
-22 (-0.1%) since 2020
Land area
1,151
square miles. A further 0.5% of the total area is water
Population density
19.0
people per square mile, computed rather than published
County seat
Colusa
Seat of county government.
Established
1850
175 years ago
Largest city
Colusa city
Population 6,519.

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 Colusa 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 Colusa County, California 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 542 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 Colusa County ranks

Position among the 58 counties of California, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn CaliforniaNationally
Population21,83650th of 581,728th of 3,144
Land area1,151 sq mi39th of 58536th of 3,144
Population density19.0 per sq mi48th of 582,280th of 3,144
Median household income$75,67236th of 58798th of 3,143

Full data for Colusa County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population21,836Vintage 2025 Population Estimates
Population in 202021,858Vintage 2025 Population Estimates
2020 estimates base?21,835Vintage 2025 Population Estimates
Land area1,151 sq mi2025 Gazetteer Files
Water area5.7 sq mi2025 Gazetteer Files
Total area1,156 sq mi2025 Gazetteer Files
Population density?19.0 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$75,672American Community Survey 2020-2024 5-Year Estimates
Median home value$393,400American Community Survey 2020-2024 5-Year Estimates
Median age35.9American Community Survey 2020-2024 5-Year Estimates
Households7,512American Community Survey 2020-2024 5-Year Estimates
Housing units8,211American 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
+51
247 births, 196 deaths
Net migration
-233
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 5 areas bordering Colusa 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
Lake CountyCalifornia63 mi67,772
Glenn CountyCalifornia50 mi28,141
Sutter CountyCalifornia40 mi98,787
Yolo CountyCalifornia27 mi224,410
Butte CountyCalifornia6.8 mi209,211

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

All 58 counties of California

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

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