Sierra County area

Sierra County, California covers 962.2 square miles: 953.2 square miles of land and 8.996 square miles of water. Its county seat is Downieville. An estimated 3,098 people lived there in 2025.

Official Census measurements · GEOID 060912026 Gazetteer · retrieved September 27, 2026
Land area953.2 mi²
Water area8.996 mi²
Population (2025)3,098
People per mi²3.3

County outline

Generalized outline of Sierra County, California
2025 Census cartographic boundary, fitted to this frame. County maps are not at a common scale. The 2026 area measurements below come from the separate Gazetteer release. Map source and limitations.

Where Sierra County is located

Sierra County highlighted on a map of all U.S. county equivalents. About the maps

Area breakdown

Land accounts for 99.1% of Sierra County’s measured area and water for 0.9%. Its combined area converts to 2,492 square kilometers or approximately 615,785 acres.

Green: land · blue: water

MeasurementSquare milesSquare kilometersAcres
Land953.1682,468.694610,027.5
Water8.99623.35,757.4
Total962.1642,491.993615,785

How Sierra County compares

By original Census land area, Sierra County ranks #45 of 58 in California and #737 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.

Its land area is 0.621 times the California county-equivalent median of 1,535.7 square miles. It accounts for 0.6% of the combined county land area in the state.

See the complete California ranking · What counts as a county equivalent?

Population and density of Sierra County

The Census Bureau estimates that 3,098 people lived in Sierra County on July 1, 2025. That ranks #3,030 of 3,222 county equivalents nationally and #57 of 58 in California. Since the April 1, 2020 estimates base of 3,232, the population has declined by 134 (−4.1%), compared with −0.5% for California as a whole.

With 953.2 square miles of land, that is 3.3 people per square mile (1.3 per km²), placing Sierra County #2,960 nationally for density and #55 in California. The median county equivalent has 47 people per square mile; the California median is 112. Put another way, there are about 197 acres of land per resident.

Estimated population, 2020–2025 · line scaled to this county’s own range
July 1202020212022202320242025
Estimate3,2263,2913,2033,1603,1213,098
Change—+65−88−43−39−23

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Sierra County

1 incorporated place lies at least partly in Sierra County. Together they are home to 709 people (22.9%); the other 2,389 (77.1%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Loyalton city, with 709 residents in the county.

Metropolitan area

Sierra County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.

ZIP codes

11 ZIP Code Tabulation Areas have land in Sierra County; 7 of them have most of their land inside the county, and the others mainly cover neighboring areas.

8943995910959229593695944959609610596118961249612596126

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Sierra County

Sierra County shares a land border with 5 county equivalents, including 1 in Nevada. It has more land than 1 of them. The largest neighbor is Washoe County (6,315.9 mi²) and the smallest is Yuba County (632 mi²). Together with its neighbors, Sierra County forms a block of 15,953.3 mi² of land, of which it holds 6%.

Map of Sierra County and the 5 county equivalents that border it Nevada County, California: 957.8 mi² landPlumas County, California: 2,553.1 mi² landWashoe County, Nevada: 6,315.9 mi² landYuba County, California: 632 mi² landLassen County, California: 4,541.4 mi² land
Sierra County (dark) and its bordering county equivalents. Select a neighbor to open its profile. Drawn from the 2025 Census cartographic boundaries in an equal-area projection. How borders are determined.
Bordering county equivalentLand mi²Size vs. SierraCompare
Washoe CountyNevada6,315.96.6× largerCompare
Lassen County4,541.44.8× largerCompare
Plumas County2,553.12.7× largerCompare
Nevada County957.8about the sameCompare
Yuba County6321.5× smallerCompare

How big is Sierra County compared with U.S. states?

Sierra County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.1 times as much. California’s county land could hold about 164 areas the size of Sierra County.

Land area: Sierra County and the closest-sized states
Sierra County953.2 mi²
Rhode Island1,033.9 mi²

Another way to picture it: the same land area would fill a square about 30.9 miles (49.7 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Sierra County?

Sierra County has more land than 2,485 of the other 3,221 county equivalents in the dataset.

Land area compared with the typical county equivalent
Sierra County953.2 mi²
California median1,535.7 mi²
National median604.5 mi²

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Sierra County at #827 nationally by total area, 90 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 0.9%, compared with a national county-equivalent median of 1.2% — 0.2 percentage points lower. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Sierra County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Land rankCounty equivalentLand mi²Comparison
#736Lake County, Florida954Compare
#737Sierra County, California953.2This county
#738Palo Pinto County, Texas952.5Compare

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.

Representative coordinates

The Census internal point is 39.576925, -120.521993. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.

Source and precision

U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 2,468,694,570 m²; AWATER: 23,299,111 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.

Download the official county source ZIP ↗ · Methodology

Common questions

How big is Sierra County?

Sierra County, California has 953.2 square miles (2,468.7 km²) of land and 8.996 square miles of water, for a total area of 962.2 square miles. It ranks #737 of 3,222 U.S. county equivalents by land area.

Is Sierra County the largest county in California?

No. Sierra County ranks #45 of 58 in California by land area. The largest is San Bernardino County, with 20,068.4 square miles of land.

What counties border Sierra County?

Sierra County shares a land border with Nevada County, Plumas County, Washoe County, Nevada, Yuba County, and Lassen County.

What is the population of Sierra County?

The Census Bureau estimates Sierra County had 3,098 residents on July 1, 2025, ranking #3,030 of 3,222 county equivalents. That is 3.3 people per square mile of land.

What is the county seat of Sierra County?

The county seat of Sierra County is Downieville.

Is Sierra County part of a metropolitan area?

No. Sierra County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.

How many ZIP codes are in Sierra County?

11 ZIP Code Tabulation Areas have land in Sierra County, and 7 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.

How does Sierra County compare with U.S. states?

It has less land than every state. Rhode Island, the smallest, has 1.1 times as much land.

How many acres of land are in Sierra County?

The land measurement converts to approximately 610,028 acres. Including water, total area is approximately 615,785 acres. One square mile equals 640 acres.

Why might another source show a different area?

Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.

Can this establish a property boundary?

No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.

Cite this county

Download the complete CSV or JSON dataset