| County | Rank | Change (2020) ↓ | 2025 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Yuba County | 1 | 7.93% | 88,460 | 81,958 |
| Madera County | 2 | 7.4% | 167,916 | 156,345 |
| San Benito County | 3 | 7.3% | 69,239 | 64,530 |
| Placer County | 4 | 7.05% | 434,535 | 405,927 |
| Merced County | 5 | 4.79% | 295,340 | 281,830 |
| Amador County | 6 | 4.74% | 42,447 | 40,525 |
| Riverside County | 7 | 4.37% | 2,528,844 | 2,422,993 |
| San Joaquin County | 8 | 4.32% | 814,309 | 780,617 |
| Calaveras County | 9 | 2.72% | 46,583 | 45,348 |
| Colusa County | 10 | 1.96% | 22,293 | 21,864 |
| Tulare County | 11 | 1.84% | 482,636 | 473,914 |
| Fresno County | 12 | 1.11% | 1,020,768 | 1,009,552 |
| San Bernardino County | 13 | 0.62% | 2,197,017 | 2,183,391 |
| Yolo County | 14 | 0.6% | 217,596 | 216,291 |
| Kern County | 15 | 0.23% | 907,958 | 905,910 |
| El Dorado County | 16 | -0.09% | 191,071 | 191,245 |
| Sacramento County | 17 | -0.16% | 1,584,104 | 1,586,566 |
| Imperial County | 18 | -0.18% | 179,291 | 179,612 |
| Stanislaus County | 19 | -0.26% | 551,838 | 553,257 |
| Mono County | 20 | -0.26% | 13,194 | 13,228 |
| San Luis Obispo County | 21 | -0.38% | 280,825 | 281,884 |
| Kings County | 22 | -0.51% | 152,072 | 152,844 |
| Solano County | 23 | -0.63% | 449,884 | 452,723 |
| Nevada County | 24 | -0.93% | 101,309 | 102,265 |
| San Diego County | 25 | -1.21% | 3,255,567 | 3,295,298 |
| Contra Costa County | 26 | -1.29% | 1,151,037 | 1,166,069 |
| Lake County | 27 | -1.33% | 67,290 | 68,199 |
| Shasta County | 28 | -1.53% | 179,224 | 182,002 |
| Butte County | 29 | -1.61% | 206,778 | 210,151 |
| Sonoma County | 30 | -1.68% | 480,098 | 488,282 |
| Sierra County | 31 | -2.14% | 3,156 | 3,225 |
| Ventura County | 32 | -2.41% | 823,028 | 843,371 |
| Tehama County | 33 | -2.43% | 64,090 | 65,687 |
| Orange County | 34 | -2.49% | 3,106,521 | 3,185,734 |
| Monterey County | 35 | -2.72% | 426,401 | 438,322 |
| Mariposa County | 36 | -2.73% | 16,651 | 17,119 |
| Santa Barbara County | 37 | -2.78% | 435,941 | 448,424 |
| Sutter County | 38 | -2.79% | 96,706 | 99,479 |
| Santa Clara County | 39 | -2.85% | 1,876,106 | 1,931,168 |
| Humboldt County | 40 | -3.08% | 132,067 | 136,262 |
| Tuolumne County | 41 | -3.5% | 53,438 | 55,379 |
| Trinity County | 42 | -3.96% | 15,454 | 16,091 |
| Marin County | 43 | -3.98% | 250,913 | 261,306 |
| Alameda County | 44 | -4.19% | 1,610,046 | 1,680,466 |
| Glenn County | 45 | -4.28% | 27,667 | 28,904 |
| Los Angeles County | 46 | -4.43% | 9,550,505 | 9,992,813 |
| Mendocino County | 47 | -4.44% | 87,310 | 91,367 |
| Inyo County | 48 | -4.69% | 18,097 | 18,987 |
| Napa County | 49 | -4.77% | 130,908 | 137,459 |
| Modoc County | 50 | -4.83% | 8,262 | 8,681 |
| Santa Cruz County | 51 | -5.29% | 256,161 | 270,474 |
| San Mateo County | 52 | -5.41% | 721,201 | 762,479 |
| Plumas County | 53 | -6.27% | 18,507 | 19,746 |
| Siskiyou County | 54 | -6.48% | 41,143 | 43,995 |
| San Francisco County | 55 | -6.79% | 811,416 | 870,518 |
| Del Norte County | 56 | -7.47% | 25,543 | 27,604 |
| Alpine County | 57 | -13.44% | 1,043 | 1,205 |
| Lassen County | 58 | -17.86% | 26,543 | 32,315 |
California's counties show varied growth patterns from 2020 to 2025. Yuba County leads with 7.93% annualized growth, followed by Madera County (7.4%) and San Benito County (7.3%). The largest counties are Los Angeles County (9,550,505), San Diego County (3,255,567), and Orange County (3,106,521). Of the 58 counties in California, 15 are growing while 43 have experienced population decline. Overall, counties averaged -1.61% annualized growth, with total population growing by -1.74% annually.