County Maps US

Sierra County, California

A county in California, ranked 57 of 58 by population.

CountyFIPS 06091

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

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Population
3,098
-128 (-4.0%) since 2020
Land area
953.2
square miles. A further 0.9% of the total area is water
Population density
3.3
people per square mile, computed rather than published
County seat
Downieville
Seat of county government.
Established
1852
173 years ago
Largest city
Loyalton city
Population 709.

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 Sierra 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 Sierra 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 424 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 Sierra 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
Population3,09857th of 582,953rd of 3,144
Land area953.2 sq mi45th of 58737th of 3,144
Population density3.3 per sq mi55th of 582,882nd of 3,144
Median household income$63,35552nd of 581,761st of 3,143

Full data for Sierra County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population3,098Vintage 2025 Population Estimates
Population in 20203,226Vintage 2025 Population Estimates
2020 estimates base?3,232Vintage 2025 Population Estimates
Land area953.2 sq mi2025 Gazetteer Files
Water area9.0 sq mi2025 Gazetteer Files
Total area962.2 sq mi2025 Gazetteer Files
Population density?3.3 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$63,355American Community Survey 2020-2024 5-Year Estimates
Median home value$331,900American Community Survey 2020-2024 5-Year Estimates
Median age54.7American Community Survey 2020-2024 5-Year Estimates
Households1,219American Community Survey 2020-2024 5-Year Estimates
Housing units2,120American 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
-26
18 births, 44 deaths
Net migration
+4
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 5 areas bordering Sierra 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
Nevada CountyCalifornia71 mi101,911
Plumas CountyCalifornia62 mi18,583
Yuba CountyCalifornia20 mi88,691
Washoe CountyNevada19 mi509,386
Lassen CountyCalifornia8.7 mi28,117

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.