County Maps US

Sonoma County, California

A county in California, ranked 17 of 58 by population.

CountyFIPS 06097

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

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Population
486,444
-2,070 (-0.4%) since 2020
Land area
1,575
square miles. A further 10.9% of the total area is water
Population density
309
people per square mile, computed rather than published
County seat
Santa Rosa
Seat of county government.
Established
1850
175 years ago
Largest city
Santa Rosa city
Population 179,437.

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 Sonoma 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 Sonoma 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 657 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 Sonoma 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
Population486,44417th of 58152nd of 3,144
Land area1,575 sq mi29th of 58385th of 3,144
Population density309 per sq mi18th of 58425th of 3,144
Median household income$104,67416th of 58126th of 3,143

Full data for Sonoma County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population486,444Vintage 2025 Population Estimates
Population in 2020488,514Vintage 2025 Population Estimates
2020 estimates base?488,860Vintage 2025 Population Estimates
Land area1,575 sq mi2025 Gazetteer Files
Water area192 sq mi2025 Gazetteer Files
Total area1,767 sq mi2025 Gazetteer Files
Population density?309 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$104,674American Community Survey 2020-2024 5-Year Estimates
Median home value$815,500American Community Survey 2020-2024 5-Year Estimates
Median age42.9American Community Survey 2020-2024 5-Year Estimates
Households190,998American Community Survey 2020-2024 5-Year Estimates
Housing units207,699American 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
+50
4,329 births, 4,279 deaths
Net migration
+988
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 6 areas bordering Sonoma 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
Napa CountyCalifornia61 mi132,949
Marin CountyCalifornia57 mi253,694
Mendocino CountyCalifornia50 mi88,122
Lake CountyCalifornia21 mi67,772
Solano CountyCalifornia6.6 mi455,376
Contra Costa CountyCaliforniaa single point1,170,070

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

Side by side

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.