County Maps US

San Diego County, California

A county in California, ranked 2 of 58 by population.

CountyFIPS 06073

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

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Population
3,282,248
-18,862 (-0.6%) since 2020
Land area
4,211
square miles. A further 7.0% of the total area is water
Population density
779
people per square mile, computed rather than published
County seat
San Diego
Seat of county government.
Established
1850
175 years ago
Largest city
San Diego city
Population 1,406,106.

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 San Diego 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 San Diego 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 632 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 San Diego 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
Population3,282,2482nd of 585th of 3,144
Land area4,211 sq mi9th of 58111th of 3,144
Population density779 per sq mi9th of 58198th of 3,144
Median household income$106,26814th of 58117th of 3,143

Full data for San Diego County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population3,282,248Vintage 2025 Population Estimates
Population in 20203,301,110Vintage 2025 Population Estimates
2020 estimates base?3,298,648Vintage 2025 Population Estimates
Land area4,211 sq mi2025 Gazetteer Files
Water area315 sq mi2025 Gazetteer Files
Total area4,526 sq mi2025 Gazetteer Files
Population density?779 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$106,268American Community Survey 2020-2024 5-Year Estimates
Median home value$854,700American Community Survey 2020-2024 5-Year Estimates
Median age37.3American Community Survey 2020-2024 5-Year Estimates
Households1,171,278American Community Survey 2020-2024 5-Year Estimates
Housing units1,250,641American 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
+12,462
35,413 births, 22,951 deaths
Net migration
-17,744
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 3 areas bordering San Diego 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
Riverside CountyCalifornia86 mi2,544,916
Imperial CountyCalifornia57 mi181,411
Orange CountyCalifornia15 mi3,149,507

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.