| County | Rank | Change (2020) ↓ | 2025 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Placer County | 1 | 9.14% | 443,045 | 405,951 |
| Yuba County | 2 | 8.83% | 89,243 | 82,001 |
| San Benito County | 3 | 8.44% | 69,977 | 64,533 |
| Madera County | 4 | 7.05% | 167,462 | 156,434 |
| San Joaquin County | 5 | 5.85% | 826,307 | 780,676 |
| Merced County | 6 | 5.72% | 299,146 | 282,963 |
| Riverside County | 7 | 5.43% | 2,556,317 | 2,424,663 |
| Yolo County | 8 | 4.51% | 227,583 | 217,768 |
| Amador County | 9 | 4.11% | 42,254 | 40,584 |
| Tulare County | 10 | 2.62% | 486,345 | 473,944 |
| Sacramento County | 11 | 2.6% | 1,627,956 | 1,586,727 |
| Kern County | 12 | 2.46% | 928,412 | 906,124 |
| Kings County | 13 | 2.45% | 156,545 | 152,797 |
| Calaveras County | 14 | 2.38% | 46,430 | 45,350 |
| San Bernardino County | 15 | 2.03% | 2,227,757 | 2,183,526 |
| Fresno County | 16 | 1.86% | 1,028,351 | 1,009,613 |
| Imperial County | 17 | 1.74% | 182,863 | 179,730 |
| Santa Clara County | 18 | 1.6% | 1,955,513 | 1,924,802 |
| Contra Costa County | 19 | 1.45% | 1,183,035 | 1,166,165 |
| Solano County | 20 | 1.38% | 459,142 | 452,887 |
| Stanislaus County | 21 | 1.14% | 560,023 | 553,710 |
| El Dorado County | 22 | 1.02% | 193,206 | 191,250 |
| Colusa County | 23 | 0.86% | 22,055 | 21,868 |
| San Diego County | 24 | 0.32% | 3,311,708 | 3,301,182 |
| Nevada County | 25 | 0.04% | 102,304 | 102,267 |
| Orange County | 26 | 0% | 3,186,307 | 3,186,261 |
| San Luis Obispo County | 27 | -0.09% | 281,679 | 281,924 |
| Mariposa County | 28 | -0.19% | 17,100 | 17,133 |
| Sonoma County | 29 | -0.23% | 487,384 | 488,501 |
| Shasta County | 30 | -0.33% | 181,586 | 182,190 |
| Butte County | 31 | -0.43% | 209,314 | 210,222 |
| Santa Barbara County | 32 | -0.58% | 445,479 | 448,083 |
| Del Norte County | 33 | -0.61% | 27,447 | 27,616 |
| Ventura County | 34 | -0.71% | 837,783 | 843,808 |
| Monterey County | 35 | -0.83% | 436,865 | 440,506 |
| Sutter County | 36 | -0.85% | 98,633 | 99,479 |
| Lake County | 37 | -0.89% | 67,594 | 68,200 |
| Alameda County | 38 | -1.23% | 1,659,978 | 1,680,614 |
| San Mateo County | 39 | -1.47% | 751,519 | 762,727 |
| Marin County | 40 | -1.63% | 257,094 | 261,341 |
| Glenn County | 41 | -1.63% | 28,418 | 28,889 |
| Los Angeles County | 42 | -2.14% | 9,782,521 | 9,996,634 |
| Mendocino County | 43 | -2.59% | 88,996 | 91,362 |
| Tehama County | 44 | -2.66% | 63,943 | 65,690 |
| Modoc County | 45 | -3.01% | 8,416 | 8,677 |
| Inyo County | 46 | -3.04% | 18,422 | 18,999 |
| Trinity County | 47 | -3.08% | 15,600 | 16,095 |
| Tuolumne County | 48 | -3.13% | 53,663 | 55,397 |
| Mono County | 49 | -3.4% | 12,775 | 13,225 |
| Santa Cruz County | 50 | -3.92% | 261,113 | 271,768 |
| Napa County | 51 | -3.97% | 132,010 | 137,465 |
| Humboldt County | 52 | -4.09% | 130,751 | 136,324 |
| Siskiyou County | 53 | -4.42% | 42,055 | 43,999 |
| San Francisco County | 54 | -4.45% | 835,901 | 874,826 |
| Sierra County | 55 | -5.67% | 3,046 | 3,229 |
| Plumas County | 56 | -6.14% | 18,548 | 19,761 |
| Alpine County | 57 | -9.08% | 1,072 | 1,179 |
| Lassen County | 58 | -13.85% | 27,842 | 32,319 |
California's counties show varied growth patterns from 2020 to 2025. Placer County leads with 9.14% annualized growth, followed by Yuba County (8.83%) and San Benito County (8.44%). The largest counties are Los Angeles County (9,782,521), San Diego County (3,311,708), and Orange County (3,186,307). Of the 58 counties in California, 26 are growing while 32 have experienced population decline. Overall, counties averaged -0.09% annualized growth, with total population growing by 0.36% annually.
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