County facts · Population growth · October 23, 2026
Fastest Growing Counties in California, 2020 to 2025
California's fastest growing counties by percent and by people added, April 2020 to July 2025 Census estimates, with each official parcel map.
Looking for the fastest growing counties in California? From the Census Bureau's April 1, 2020 estimates base to its July 1, 2025 estimate, California went from about 39,555,703 to 39,355,309 residents, a change of −200,394 (−0.5%). The fastest growing county by percentage was Placer County (+9.2%), while Riverside County added the most people (+124,954, +5.2%).
Each table links the county's Platbookmapper page and its official parcel viewer, so you can go from the growth numbers straight to the property lines.
California growth at a glance
- County: 58
- Statewide, April 2020 to July 2025: −200,394 residents (−0.5%); July 2024 to July 2025 alone: −9,465 (−0.0%)
- Grew: 22 of 58 · Lost residents: 36
- Fastest growing by percent: Placer County (+9.2%); most people added: Riverside County (+124,954)
- Counties with more deaths than births over the period: 25 of 58
The 10 fastest growing California counties by percent
| # | County | Apr 2020 | Jul 2025 | Change | % change | Parcel viewer |
|---|---|---|---|---|---|---|
| 1 | Placer County | 404,767 | 442,081 | +37,314 | +9.2% | ArcGIS Experience Builder |
| 2 | San Benito County | 64,205 | 70,082 | +5,877 | +9.2% | ArcGIS Experience Builder |
| 3 | Yuba County | 81,573 | 88,691 | +7,118 | +8.7% | ArcGIS Map Viewer |
| 4 | Madera County | 156,258 | 167,927 | +11,669 | +7.5% | listed link under review |
| 5 | San Joaquin County | 779,234 | 823,815 | +44,581 | +5.7% | county web map |
| 6 | Merced County | 282,457 | 297,260 | +14,803 | +5.2% | listed link under review |
| 7 | Riverside County | 2,419,962 | 2,544,916 | +124,954 | +5.2% | county web map |
| 8 | Amador County | 40,487 | 41,876 | +1,389 | +3.4% | ArcGIS Experience Builder |
| 9 | Yolo County | 217,871 | 224,410 | +6,539 | +3.0% | ArcGIS Experience Builder |
| 10 | Calaveras County | 45,285 | 46,605 | +1,320 | +2.9% | ArcGIS Web AppBuilder |
These 10 added about 255,564 people combined. The median county changed by −0.8%.
The 10 counties that added the most people
| # | County | People added | % change | Jul 2025 | Parcel viewer |
|---|---|---|---|---|---|
| 1 | Riverside County | +124,954 | +5.2% | 2,544,916 | county web map |
| 2 | San Joaquin County | +44,581 | +5.7% | 823,815 | county web map |
| 3 | San Bernardino County | +42,438 | +1.9% | 2,224,091 | county web map |
| 4 | Placer County | +37,314 | +9.2% | 442,081 | ArcGIS Experience Builder |
| 5 | Sacramento County | +33,433 | +2.1% | 1,618,460 | county web map |
| 6 | Fresno County | +26,795 | +2.7% | 1,035,456 | ArcGIS Web AppBuilder |
| 7 | Kern County | +17,841 | +2.0% | 927,068 | county web map |
| 8 | Merced County | +14,803 | +5.2% | 297,260 | listed link under review |
| 9 | Tulare County | +12,028 | +2.5% | 485,146 | ArcGIS Web AppBuilder |
| 10 | Madera County | +11,669 | +7.5% | 167,927 | listed link under review |
The top 10 account for about 91% of all the gains in the counties that grew.
Where the new residents came from
The Census Bureau splits each change into natural change (births minus deaths), net domestic migration (moves from other parts of the US) and net international migration. Totals for April 2020 to July 2025 in the five fastest growing counties:
| County | Births minus deaths | Net domestic moves | Net international moves | Total change |
|---|---|---|---|---|
| Placer County | −213 | +32,091 | +5,624 | +37,314 |
| San Benito County | +1,865 | +3,799 | +305 | +5,877 |
| Yuba County | +2,113 | +4,306 | +678 | +7,118 |
| Madera County | +4,200 | +5,972 | +1,590 | +11,669 |
| San Joaquin County | +16,691 | +6,034 | +21,859 | +44,581 |
In 4 of these 5, moves from elsewhere in the US were the biggest source of growth. The three parts do not add up exactly to the total because the Census Bureau also carries a small residual.
The last year alone: July 2024 to July 2025
- Placer County: +1.8% (+7,802)
- San Benito County: +1.4% (+997)
- Yuba County: +1.4% (+1,250)
- Madera County: +1.1% (+1,795)
- San Joaquin County: +0.8% (+6,666)
5 of these 5 are also in the 2020–2025 top 10, so the growth is not a one-year blip.
Counties losing residents
36 of California's 58 counties had fewer residents in July 2025 than in April 2020. The steepest declines:
- Lassen County: −14.1% (−4,612, now about 28,117)
- Alpine County: −11.5% (−135, now about 1,043)
- Plumas County: −6.1% (−1,211, now about 18,583)
- San Francisco County: −6.0% (−52,471, now about 826,079)
- Mono County: −5.3% (−694, now about 12,505)
What fast growth means on a parcel map
- New lots show up as plats first. When land is subdivided, the plat is recorded with the county and the parcel layer catches up on its own schedule, so a brand-new lot may not appear on the map for a while. Check the recorder's recent plats if a parcel looks missing.
- Parcel numbers change after splits. A tract that was one parcel last year can be several today. Search by owner name or address as well as by an old parcel number.
- City limits move. Growing cities annex land, which changes who handles zoning and permits even though the county still keeps the deed and the tax map.
- Percent is not the same as people. A small county can post a big percentage on a modest number of new residents, so read the people-added column too.
Related guides
- Largest counties in California
- California county GIS websites by viewer
- California plat maps
- California parcel map guide
- California landowner maps for hunting
- Fastest growing counties in the US
- US counties losing population
More: All California counties on Platbookmapper
Sources
- U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2025 (April 1, 2020 estimates base and July 1, 2020–2025 estimates, with components of change). Percent change is from the April 1, 2020 estimates base to the July 1, 2025 estimate.
- Platbookmapper county GIS directory (live data file behind our county pages, pulled October 23, 2026) for each official parcel viewer.