(Links below lead to Quick Facts for California Counties: People, Business & Geography at U.S. Census Bureau.)
| Area | 7/1/2009 | 7/1/2008 | 7/1/2007 | 7/1/2006 | 7/1/2005 | 7/1/2004 | 7/1/2003 | 7/1/2002 | 7/1/2001 | 7/1/2000 | Census 2000 |
| California | 36,961,664 | 36,580,371 | 36,226,122 | 35,979,208 | 35,795,255 | 35,558,419 | 35,251,107 | 34,876,194 | 34,485,623 | 33,994,571 | 33,871,648 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Alameda County | 1,491,482 | 1,470,326 | 1,449,020 | 1,438,193 | 1,436,453 | 1,441,781 | 1,450,968 | 1,460,576 | 1,468,918 | 1,450,220 | 1,443,741 |
| Alpine County | 1,041 | 1,057 | 1,144 | 1,158 | 1,123 | 1,182 | 1,172 | 1,195 | 1,175 | 1,205 | 1,208 |
| Amador County | 37,876 | 37,980 | 38,480 | 38,072 | 37,788 | 37,213 | 36,860 | 36,506 | 35,700 | 35,173 | 35,100 |
| Butte County | 220,577 | 219,503 | 217,741 | 216,933 | 214,831 | 213,173 | 211,584 | 209,319 | 206,384 | 203,926 | 203,171 |
| Calaveras County | 46,731 | 46,944 | 46,852 | 46,524 | 45,688 | 44,852 | 44,007 | 42,583 | 41,433 | 40,696 | 40,554 |
| Colusa County | 21,321 | 21,155 | 21,100 | 20,889 | 20,541 | 20,219 | 19,579 | 19,264 | 19,042 | 18,829 | 18,804 |
| Contra Costa County | 1,041,274 | 1,025,464 | 1,010,542 | 1,001,303 | 999,271 | 992,747 | 987,662 | 980,446 | 971,487 | 953,192 | 948,816 |
| Del Norte County | 29,114 | 28,873 | 28,746 | 28,441 | 28,471 | 28,085 | 27,722 | 27,485 | 27,341 | 27,471 | 27,507 |
| El Dorado County | 178,447 | 177,009 | 175,752 | 174,995 | 173,500 | 170,486 | 167,436 | 164,675 | 160,848 | 157,134 | 156,299 |
| Fresno County | 915,267 | 903,133 | 889,888 | 878,024 | 867,438 | 857,162 | 844,194 | 828,245 | 812,426 | 801,444 | 799,407 |
| Glenn County | 28,299 | 28,127 | 27,862 | 27,714 | 27,452 | 27,193 | 27,071 | 26,705 | 26,487 | 26,451 | 26,453 |
| Humboldt County | 129,623 | 128,852 | 128,564 | 129,033 | 128,943 | 128,694 | 128,219 | 127,779 | 127,002 | 126,403 | 126,518 |
| Imperial County | 166,874 | 163,093 | 160,366 | 156,792 | 153,047 | 149,909 | 147,254 | 144,579 | 143,152 | 142,396 | 142,361 |
| Inyo County | 17,293 | 17,223 | 17,438 | 17,499 | 17,737 | 17,974 | 18,127 | 18,079 | 17,945 | 17,918 | 17,945 |
| Kern County | 807,407 | 797,145 | 784,687 | 768,209 | 747,315 | 726,029 | 706,963 | 689,204 | 674,028 | 663,484 | 661,645 |
| Kings County | 148,764 | 148,746 | 147,622 | 145,168 | 143,178 | 142,151 | 138,714 | 134,681 | 132,453 | 129,774 | 129,461 |
| Lake County | 65,279 | 65,092 | 64,644 | 64,623 | 64,143 | 63,390 | 62,692 | 61,674 | 60,321 | 58,551 | 58,309 |
| Lassen County | 34,473 | 34,547 | 35,005 | 34,078 | 34,037 | 34,102 | 33,695 | 33,300 | 33,503 | 33,749 | 33,828 |
| Los Angeles County | 9,848,011 | 9,779,254 | 9,734,701 | 9,760,598 | 9,803,912 | 9,808,494 | 9,777,324 | 9,717,871 | 9,634,764 | 9,542,578 | 9,519,338 |
| Madera County | 148,632 | 147,577 | 145,223 | 142,865 | 139,672 | 136,516 | 132,017 | 127,841 | 125,423 | 123,566 | 123,109 |
| Marin County | 250,750 | 248,345 | 246,100 | 244,336 | 244,024 | 243,677 | 245,030 | 246,332 | 247,958 | 247,614 | 247,289 |
| Mariposa County | 17,792 | 17,960 | 17,963 | 17,896 | 17,714 | 17,656 | 17,585 | 17,202 | 17,106 | 17,143 | 17,130 |
| Mendocino County | 86,040 | 85,786 | 85,560 | 85,959 | 86,803 | 87,092 | 87,415 | 86,911 | 86,614 | 86,396 | 86,265 |
| Merced County | 245,321 | 244,356 | 243,083 | 240,516 | 237,901 | 233,529 | 228,993 | 223,666 | 217,937 | 212,122 | 210,554 |
| Modoc County | 9,107 | 9,089 | 9,100 | 9,252 | 9,261 | 9,359 | 9,319 | 9,240 | 9,291 | 9,415 | 9,449 |
| Mono County | 12,927 | 12,881 | 12,825 | 13,102 | 12,888 | 12,919 | 13,043 | 13,191 | 13,125 | 12,896 | 12,853 |
| Monterey County | 410,370 | 405,660 | 402,116 | 401,374 | 405,090 | 408,867 | 410,419 | 409,210 | 407,065 | 403,065 | 401,762 |
| Napa County | 134,650 | 133,591 | 131,949 | 130,818 | 129,859 | 130,007 | 129,800 | 128,584 | 126,731 | 124,545 | 124,279 |
| Nevada County | 97,751 | 97,297 | 96,942 | 96,772 | 96,554 | 95,974 | 95,195 | 94,412 | 93,594 | 92,503 | 92,033 |
| Orange County | 3,026,786 | 2,989,141 | 2,957,902 | 2,953,062 | 2,957,263 | 2,956,096 | 2,940,109 | 2,917,106 | 2,890,972 | 2,856,372 | 2,846,289 |
| Placer County | 348,552 | 341,041 | 331,870 | 324,213 | 314,619 | 304,386 | 291,883 | 277,833 | 264,221 | 251,274 | 248,399 |
| Plumas County | 20,122 | 20,359 | 20,606 | 20,704 | 20,957 | 20,963 | 20,929 | 20,861 | 20,825 | 20,764 | 20,824 |
| Riverside County | 2,125,440 | 2,087,917 | 2,055,924 | 1,994,840 | 1,917,401 | 1,845,631 | 1,763,765 | 1,682,749 | 1,614,698 | 1,559,109 | 1,545,387 |
| Sacramento County | 1,400,949 | 1,386,469 | 1,373,585 | 1,362,328 | 1,354,695 | 1,344,279 | 1,324,971 | 1,299,105 | 1,265,432 | 1,230,150 | 1,223,499 |
| San Benito County | 55,058 | 54,797 | 54,505 | 54,468 | 54,930 | 55,090 | 55,376 | 55,217 | 54,752 | 53,827 | 53,234 |
| San Bernardino County | 2,017,673 | 2,004,914 | 1,992,989 | 1,973,664 | 1,943,934 | 1,899,689 | 1,847,860 | 1,800,599 | 1,761,558 | 1,718,469 | 1,709,434 |
| San Diego County | 3,053,793 | 3,019,274 | 2,975,656 | 2,947,222 | 2,941,770 | 2,935,672 | 2,926,814 | 2,901,235 | 2,867,094 | 2,824,987 | 2,813,833 |
| San Francisco County | 815,358 | 808,001 | 799,185 | 786,149 | 777,660 | 773,284 | 775,046 | 779,281 | 784,631 | 777,360 | 776,733 |
| San Joaquin County | 674,860 | 668,753 | 665,246 | 659,897 | 654,451 | 640,964 | 625,236 | 608,367 | 591,000 | 567,968 | 563,598 |
| San Luis Obispo County | 266,971 | 265,134 | 261,706 | 259,366 | 257,567 | 256,095 | 254,240 | 252,932 | 251,499 | 247,878 | 246,681 |
| San Mateo County | 718,989 | 708,100 | 697,339 | 692,802 | 692,199 | 692,033 | 694,437 | 699,043 | 706,634 | 708,272 | 707,161 |
| Santa Barbara County | 407,057 | 403,655 | 400,499 | 398,656 | 400,256 | 401,130 | 402,366 | 402,079 | 401,456 | 399,784 | 399,347 |
| Santa Clara County | 1,784,642 | 1,755,849 | 1,723,927 | 1,700,089 | 1,682,383 | 1,668,984 | 1,667,762 | 1,673,028 | 1,690,395 | 1,685,842 | 1,682,585 |
| Santa Cruz County | 256,218 | 252,929 | 250,126 | 248,758 | 248,957 | 250,420 | 251,559 | 253,708 | 255,644 | 255,834 | 255,602 |
| Shasta County | 181,099 | 180,515 | 179,334 | 178,449 | 177,537 | 176,467 | 174,417 | 171,141 | 166,968 | 163,782 | 163,256 |
| Sierra County | 3,174 | 3,250 | 3,312 | 3,371 | 3,332 | 3,394 | 3,479 | 3,462 | 3,506 | 3,569 | 3,555 |
| Siskiyou County | 44,634 | 44,535 | 44,222 | 44,220 | 44,409 | 44,229 | 44,163 | 43,908 | 43,894 | 44,230 | 44,301 |
| Solano County | 407,234 | 406,293 | 405,994 | 406,181 | 406,605 | 408,346 | 408,397 | 407,855 | 403,862 | 396,974 | 394,542 |
| Sonoma County | 472,102 | 466,424 | 461,424 | 459,783 | 461,359 | 463,211 | 463,715 | 463,593 | 464,454 | 460,411 | 458,614 |
| Stanislaus County | 510,385 | 507,450 | 506,411 | 502,989 | 498,592 | 491,558 | 486,512 | 477,197 | 463,783 | 449,702 | 446,997 |
| Sutter County | 92,614 | 92,127 | 91,497 | 89,746 | 87,670 | 85,653 | 84,067 | 81,767 | 79,941 | 79,149 | 78,930 |
| Tehama County | 61,138 | 61,143 | 60,764 | 60,374 | 59,587 | 58,784 | 57,933 | 57,000 | 56,474 | 56,136 | 56,039 |
| Trinity County | 14,165 | 14,015 | 13,933 | 13,865 | 13,631 | 13,328 | 13,336 | 13,158 | 12,916 | 13,006 | 13,022 |
| Tulare County | 429,668 | 422,343 | 416,189 | 409,641 | 403,653 | 394,996 | 386,399 | 378,285 | 372,592 | 368,628 | 368,021 |
| Tuolumne County | 55,175 | 55,616 | 55,681 | 56,068 | 56,267 | 56,185 | 56,213 | 55,681 | 55,162 | 54,651 | 54,501 |
| Ventura County | 802,983 | 794,778 | 789,671 | 788,073 | 786,058 | 787,749 | 783,840 | 776,560 | 765,278 | 756,366 | 753,197 |
| Yolo County | 199,407 | 196,619 | 193,912 | 189,082 | 185,850 | 184,993 | 182,762 | 180,290 | 175,390 | 169,884 | 168,660 |
| Yuba County | 72,925 | 72,865 | 71,698 | 70,012 | 67,029 | 64,378 | 63,462 | 62,399 | 61,339 | 60,334 | 60,219 |
Source: Population Division, U.S. Census Bureau