| Rank |
County |
Population (2012) |
| 1 |
Los Angeles County, California
|
9,962,789
|
| 2 |
San Diego County, California
|
3,177,063
|
| 3 |
Orange County, California
|
3,090,132
|
| 4 |
Riverside County, California
|
2,268,783
|
| 5 |
San Bernardino County, California
|
2,081,313
|
| 6 |
Santa Clara County, California
|
1,837,504
|
| 7 |
Alameda County, California
|
1,554,720
|
| 8 |
Sacramento County, California
|
1,450,121
|
| 9 |
Contra Costa County, California
|
1,079,597
|
| 10 |
Fresno County, California
|
947,895
|
| 11 |
Kern County, California
|
856,158
|
| 12 |
Ventura County, California
|
835,981
|
| 13 |
San Francisco County, California
|
825,863
|
| 14 |
San Mateo County, California
|
739,311
|
| 15 |
San Joaquin County, California
|
702,612
|
| 16 |
Stanislaus County, California
|
521,726
|
| 17 |
Sonoma County, California
|
491,829
|
| 18 |
Tulare County, California
|
451,977
|
| 19 |
Santa Barbara County, California
|
431,249
|
| 20 |
Monterey County, California
|
426,762
|
| 21 |
Solano County, California
|
420,757
|
| 22 |
Placer County, California
|
361,682
|
| 23 |
San Luis Obispo County, California
|
274,804
|
| 24 |
Santa Cruz County, California
|
266,776
|
| 25 |
Merced County, California
|
262,305
|
| 26 |
Marin County, California
|
256,069
|
| 27 |
Butte County, California
|
221,539
|
| 28 |
Yolo County, California
|
204,118
|
| 29 |
El Dorado County, California
|
180,561
|
| 30 |
Shasta County, California
|
178,586
|
| 31 |
Imperial County, California
|
176,948
|
| 32 |
Madera County, California
|
152,218
|
| 33 |
Kings County, California
|
151,364
|
| 34 |
Napa County, California
|
139,045
|
| 35 |
Humboldt County, California
|
134,827
|
| 36 |
Nevada County, California
|
98,292
|
| 37 |
Sutter County, California
|
95,022
|
| 38 |
Mendocino County, California
|
87,428
|
| 39 |
Yuba County, California
|
72,926
|
| 40 |
Lake County, California
|
63,983
|
| 41 |
Tehama County, California
|
63,406
|
| 42 |
San Benito County, California
|
56,884
|
| 43 |
Tuolumne County, California
|
54,008
|
| 44 |
Calaveras County, California
|
44,742
|
| 45 |
Siskiyou County, California
|
44,154
|
| 46 |
Amador County, California
|
37,035
|
| 47 |
Lassen County, California
|
33,658
|
| 48 |
Del Norte County, California
|
28,290
|
| 49 |
Glenn County, California
|
27,992
|
| 50 |
Colusa County, California
|
21,411
|
| 51 |
Plumas County, California
|
19,399
|
| 52 |
Inyo County, California
|
18,495
|
| 53 |
Mariposa County, California
|
17,905
|
| 54 |
Mono County, California
|
14,348
|
| 55 |
Trinity County, California
|
13,526
|
| 56 |
Modoc County, California
|
9,327
|
| 57 |
Sierra County, California
|
3,086
|
| 58 |
Alpine County, California
|
1,129
|