The U.S. state of California is divided into 58 counties. Explore list of California Counties and their County Seats in alphabetical order and check their population, areas and the date of formation.
List of California Counties and County Seat
| County | County Seat | Population (2011) | Area | Formed |
|---|---|---|---|---|
| Alameda County | Oakland | 1638215 | 738 sq mi | 1853 |
| Alpine County | Markleeville | 1110 | 739 sq mi | 1864 |
| Amador County | Jackson | 37001 | 606 sq mi | 1854 |
| Butte County | Oroville | 225411 | 1,640 sq mi | 1850 |
| Calaveras County | San Andreas | 44828 | 1,020 sq mi | 1850 |
| City and County of San Francisco | San Francisco | 864816 | 47 sq mi | 1850 |
| Colusa County | Colusa | 21482 | 1,151 sq mi | 1850 |
| Contra Costa County | Martinez | 1126745 | 720 sq mi | 1850 |
| Del Norte County | Crescent City | 27254 | 1,008 sq mi | 1857 |
| El Dorado County | Placerville | 184452 | 1,712 sq mi | 1850 |
| Fresno County | Fresno | 974861 | 5,963 sq mi | 1856 |
| Glenn County | Willows | 28017 | 1,315 sq mi | 1891 |
| Humboldt County | Eureka | 135727 | 3,573 sq mi | 1853 |
| Imperial County | El Centro | 180191 | 4,175 sq mi | 1907 |
| Inyo County | Independence | 18260 | 10,192 sq mi | 1866 |
| Kern County | Bakersfield | 882176 | 8,142 sq mi | 1866 |
| Kings County | Hanford | 150965 | 1,390 sq mi | 1893 |
| Lake County | Lakeport | 64591 | 1,258 sq mi | 1861 |
| Lassen County | Susanville | 31345 | 4,558 sq mi | 1864 |
| Los Angeles County | Los Angeles | 10170292 | 4,060 sq mi | 1850 |
| Madera County | Madera | 154998 | 2,138 sq mi | 1893 |
| Marin County | San Rafael | 261221 | 520 sq mi | 1850 |
| Mariposa County | Mariposa | 17531 | 1,451 sq mi | 1850 |
| Mendocino County | Ukiah | 87649 | 3,509 sq mi | 1850 |
| Merced County | Merced | 268455 | 1,929 sq mi | 1855 |
| Modoc County | Alturas | 8965 | 3,944 sq mi | 1874 |
| Mono County | Bridgeport | 13909 | 3,044 sq mi | 1861 |
| Monterey County | Salinas | 433898 | 3,322 sq mi | 1850 |
| Napa County | Napa | 142456 | 754 sq mi | 1850 |
| Nevada County | Nevada City | 98877 | 958 sq mi | 1851 |
| Orange County | Santa Ana | 3169776 | 790 sq mi | 1889 |
| Placer County | Auburn | 375391 | 1,503 sq mi | 1851 |
| Plumas County | Quincy | 18409 | 2,554 sq mi | 1854 |
| Riverside County | Riverside | 2361026 | 7,208 sq mi | 1893 |
| Sacramento County | Sacramento | 1501335 | 966 sq mi | 1850 |
| San Benito County | Hollister | 58792 | 1,389 sq mi | 1874 |
| San Bernardino County | San Bernardino | 2128133 | 20,062 sq mi | 1853 |
| San Diego County | San Diego | 3299521 | 4,204 sq mi | 1850 |
| San Joaquin County | Stockton | 726106 | 1,399 sq mi | 1850 |
| San Luis Obispo County | San Luis Obispo | 281401 | 3,304 sq mi | 1850 |
| San Mateo County | Redwood City | 765135 | 449 sq mi | 1856 |
| Santa Barbara County | Santa Barbara | 444769 | 2,738 sq mi | 1850 |
| Santa Clara County | San Jose | 1918044 | 1,291 sq mi | 1850 |
| Santa Cruz County | Santa Cruz | 274146 | 446 sq mi | 1850 |
| Shasta County | Redding | 179533 | 3,786 sq mi | 1850 |
| Sierra County | Downieville | 2967 | 953 sq mi | 1852 |
| Siskiyou County | Yreka | 43554 | 6,287 sq mi | 1852 |
| Solano County | Fairfield | 436092 | 828 sq mi | 1850 |
| Sonoma County | Santa Rosa | 502146 | 1,576 sq mi | 1850 |
| Stanislaus County | Modesto | 538388 | 1,495 sq mi | 1854 |
| Sutter County | Yuba City | 96463 | 603 sq mi | 1850 |
| Tehama County | Red Bluff | 63308 | 2,951 sq mi | 1856 |
| Trinity County | Weaverville | 13069 | 3,179 sq mi | 1850 |
| Tulare County | Visalia | 459863 | 4,824 sq mi | 1852 |
| Tuolumne County | Sonora | 53709 | 2,236 sq mi | 1850 |
| Ventura County | Ventura | 850536 | 1,846 sq mi | 1872 |
| Yolo County | Woodland | 213016 | 1,012 sq mi | 1850 |
| Yuba County | Marysville | 74492 | 630 sq mi | 1850 |
