California Counties: History and Information

Focused on the histories of California counties

Creation of the First Eighteen California Counties

On January 4, 1850, a committee of California's first constitutional convention, chaired by General Mariano Vallejo, recommended the creation of eighteen counties. They were Benicia, Butte, Fremont, Los Angeles, Mariposa, Monterey, Mt. Diablo, Oro, Redding, Sacramento, San Diego, San Francisco, San Joaquin, San Jose, San Luis Obispo, Santa Barbara, Sonoma, and Sutter.

The next nine California Counties

Between January 4 and February 18, 1850, the California legislature added nine counties to the list recommended by General Vallejo's committee, some of the changes based on additional recommendations by the committee. The nine added counties were Branciforte, Calaveras, Coloma, Colusi, Marin, Mendocino, Napa, Trinity, and Yuba. This brought the total number of counties to 27. The legislature also approved several name changes. Benicia was renamed El Dorado, Fremont was renamed Yola, Mt. Diablo was renamed Contra Costa, San Jose was renamed Santa Clara, Oro was renamed Tuolumne, and Redding was renamed Shasta.

Most of California's counties were named by Spanish explorers, often for a Roman Catholic saint whose feast day intersected with the advance into a new part of Alta California. Native American names are also represented, with a smattering of counties named for local figures from the early American era. Many counties are named after Spanish missions.

Effective February 18, 1850, twenty-seven counties were created in California. The new counties were Branciforte, Butte, Calaveras, Colusi, Contra Costa, El Dorado, Los Angeles, Marin, Mariposa, Mendocino, Monterey, Napa, Sacramento, San Diego, San Francisco, San Joaquin, San Luis Obispo, Santa Barbara, Santa Clara, Solano, Sonoma, Sutter, Trinity, Tuolumne, Yola, and Yuba.

In early 1850, not long after the legislature adopted its first statute creating counties, new statutes were adopted changing some county names. Branciforte was changed to Santa Cruz, Colusi was changed to Colusa, and Yola was changed to Yolo.

On September 9, 1850, California became the State of California with the same twenty-seven counties.

The last California county to have been established is Imperial County in 1907.