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 9,550,505. The most recent census shows that its population has decreased by 0.04% 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 : 3,255,567
• Orange County : 3,106,521

California Counties with the Fewest Residents

The smallest county in California is Alpine County , with a population of just 1,043. This total represents a decrease of 0.1% since the last census count was performed.

Other small counties include:

• Sierra County : 3,156
• Modoc County : 8,262
• Mono County : 13,194

California Counties with Rapid Growth

Yuba County , with its current population of 88,460, has shown the largest population growth, with an increase of 0.1% since the last census.

Riverside County has also had relatively high population growth of 0.04% with 2,528,844 residents.

On the other hand, Lassen County has had the largest decrease in population, with its 26,543 current residents totalling 0.2% less than the previous census.