California Counties by Population (2025)

There are 58 counties in California.

Los Angeles County is the largest county in the state, with a population of 9,782,521. The most recent census shows that its population has decreased by 0.02% since the previous census.

A number of other California counties also boast relatively large populations for their state, though not able to match the density of Los Angeles County:

• San Diego County : 3,311,708
• Orange County : 3,186,307

California Counties with the Fewest Residents

The smallest county in California is Alpine County , with a population of just 1,072. This total represents a decrease of 0.1% since the last census count was performed.

Other small counties include:

• Sierra County : 3,046
• Modoc County : 8,416
• Mono County : 12,775

California Counties with Rapid Growth

Placer County , with its sizeable population of 443,045, has shown the largest population growth, with an increase of 0.1% since the last census.

San Joaquin County has also had relatively high population growth of 0.06% with 826,307 residents.

On the other hand, Lassen County has had the largest decrease in population, with its 27,842 current residents totalling 0.1% less than the previous census.