
Lassen County
- State:
- California
- County Seat:
- Susanville
Lassen County's estimated 2025 population is 26,543 with a growth rate of -4.18% in the past year according to the most recent United States census data. Lassen County is the 48th largest county in California. The 2010 population was 34,828 and has seen a growth of -23.79% since that time.