Placer County area

Population and density of Placer County

The Census Bureau estimates that 442,081 people lived in Placer County on July 1, 2025. That ranks #169 of 3,222 county equivalents nationally and #20 of 58 in California. Since the April 1, 2020 estimates base of 404,767, the population has grown by 37,314 (+9.2%), compared with −0.5% for California as a whole.

With 1,407.4 square miles of land, that is 314 people per square mile (121 per km²), placing Placer County #492 nationally for density and #17 in California. The median county equivalent has 47 people per square mile; the California median is 112. Put another way, there are about 2 acres of land per resident.

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 Placer County

6 incorporated places lie at least partly in Placer County. Together they are home to 324,384 people (73.4%); the other 117,697 (26.6%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Roseville city, with 167,302 residents in the county. The county seat, Auburn city, has 13,847 residents. Among places with at least 1,000 residents in 2020, Lincoln city grew fastest since then (+15.3%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Placer County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Placer County is a central county of the Sacramento-Roseville-Folsom, CA Metropolitan Statistical Area. Its 4 county equivalents have 2,477,274 residents on 5,093.6 square miles of land; Placer County accounts for 27.6% of the land and 17.8% of the residents. By combined land it ranks #50 of 393 metropolitan areas, and #27 by population. It belongs to the Sacramento-Roseville, CA Combined Statistical Area.

ZIP codes

34 ZIP Code Tabulation Areas have land in Placer County; 30 of them have most of their land inside the county, and the others mainly cover neighboring areas.

95602956039560495626956319564895650956589566195663956689567795678956819570195703957139571495715957179572295728957369574695747957659614096141961429614396145961469614896161

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 Placer County

Placer County shares a land border with 8 county equivalents, including 3 in Nevada. It has more land than 6 of them. The largest neighbor is Washoe County (6,315.9 mi²) and the smallest is Carson City (144.5 mi²). Together with its neighbors, Placer County forms a block of 13,444 mi² of land, of which it holds 10.5%.

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

Placer County has more land than 1 of the 50 states. It is about 1.4 times the land area of Rhode Island (1,033.9 mi²), while Delaware, the next larger state, has 1.4 times as much land (1,948.6 mi²). California’s county land could hold about 111 areas the size of Placer County.

Another way to picture it: the same land area would fill a square about 37.5 miles (60.4 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 Placer County?

Placer County has more land than 2,795 of the other 3,221 county equivalents in the dataset.

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 Placer County at #449 nationally by total area, 22 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 6.3%, compared with a national county-equivalent median of 1.2% — 5.1 percentage points higher. 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 Placer County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

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.