The original 27 County's beginning at California's Statehood.
| 4 | Butte | 5 | Calaveras | 6 | Colusa | 7 | Contra Costa |
| 9 | El Dorado | 20 | Los Angeles | 22 | Marin | 23 | Mariposa |
| 24 | Mendocino | 28 | Monterey | 29 | Napa | 35 | Sacramento |
| 38 | San Diego | 39 | San Francisco | 40 | San Joaquin | 41 | San Luis Obispo |
| 43 | Santa Barbara | 44 | Santa Clara | 45 | Santa Cruz | 46 | Shasta |
| 49 | Solano | 50 | Sonoma | 52 | Sutter | 54 | Trinity |
| 56 | Tuolumne | 58 | Yolo | 59 | Yuba |