Mendocino County area

Population and density of Mendocino County

The Census Bureau estimates that 88,122 people lived in Mendocino County on July 1, 2025. That ranks #685 of 3,222 county equivalents nationally and #39 of 58 in California. Since the April 1, 2020 estimates base of 91,585, the population has declined by 3,463 (−3.8%), compared with −0.5% for California as a whole.

With 3,506.8 square miles of land, that is 25 people per square mile (9.7 per km²), placing Mendocino County #2,143 nationally for density and #44 in California. The median county equivalent has 47 people per square mile; the California median is 112. Put another way, there are about 25 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 Mendocino County

4 incorporated places lie at least partly in Mendocino County. Together they are home to 28,227 people (32%); the other 59,895 (68%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Ukiah city, with 16,068 residents in the county.

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

Metropolitan area

Mendocino County is a central county of the Ukiah, CA Micropolitan Statistical Area. Mendocino County is the area’s only county equivalent, so the micro area has the same 3,506.8 square miles of land. By combined land it ranks #41 of 542 micropolitan areas, and #54 by population.

ZIP codes

29 ZIP Code Tabulation Areas have land in Mendocino County; 26 of them have most of their land inside the county, and the others mainly cover neighboring areas.

9541095415954179542095425954279542895429954329543795445954499545495456954599546095463954669546895469954709548295488954909549495542955859558795589

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 Mendocino County

Mendocino County shares a land border with 6 county equivalents. It has more land than 5 of them. The largest neighbor is Humboldt County (3,568 mi²) and the smallest is Lake County (1,255.1 mi²). Together with its neighbors, Mendocino County forms a block of 17,347.6 mi² of land, of which it holds 20.2%.

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

Mendocino County has more land than 2 of the 50 states. It is about 1.8 times the land area of Delaware (1,948.6 mi²), while Connecticut, the next larger state, has 1.4 times as much land (4,842.5 mi²). California’s county land could hold about 44 areas the size of Mendocino County.

Another way to picture it: the same land area would fill a square about 59.2 miles (95.3 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 Mendocino County?

Mendocino County has more land than 3,079 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 Mendocino County at #133 nationally by total area, 10 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.

Its water share is 9.6%, compared with a national county-equivalent median of 1.2% — 8.4 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 Mendocino 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.