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Today’s California counties did not always exist in the present form. They went through many different changes in the space of a few short years.
The 27 Original Counties Of California
A committee of California’s first constitutional convention was convened on January 4, 1850. At this meeting, it was suggested that California be split into 18 counties.
The 18 counties 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 Counties
The committee later suggested some other changes and on February 18, 1850, the following 9 counties were added to the 18 counties, making a total of 27 counties:
The 9 counties were Branciforte, Calaveras, Coloma, Colusi, Marin, Mendocino, Napa, Trinity and Yuba Counties
The committee also changed the names of several of the original counties at that time.
Those changes were Benicia to El Dorado, Fremont to Yola, Mt. Diablo to Contra Costa, San Jose to Santa Clara, Oro to Tuolumne, Redding to Shasta
This meant that, as of February 18, 1850, the 27 counties in California 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, Shasta, Solano, Sonoma, Sutter, Trinity, Tuolumne, Yola, Yuba
Then, a little later in 1850, some legislature was adopted that caused some of the county names to change yet again. Branciforte became Santa Cruz and Colusi became Colusa. Yola, meanwhile, was changed to Yolo.
However, 32 more counties were created in the state after 1850. Of the original 27, only Marin county stayed exactly as it was, neither losing nor gaining land.
Of the 32 created later, only 7 stayed as they were upon their creation. Those 7 are: Alameda, Alpine, Imperial, Madera, Modoc, Orange, Riverside
The State of California entered the union as the 31st state by Congress on September 9, 1850, as part of the Compromise of 1850.
California Counties Today
California has counties that no longer are in existence. A lot of these counties were established and disbanded within the 19th century; county borders have modified very little since 1900 in the vast most of states.
Fun Facts about California Counties
- California was first divided into 27 counties on February 18, 1850.
- These were further sub-divided to form 16 additional counties by 1860.
- Another 14 counties formed through further subdivision from 1861 to 1893.
Counties by Name
More California counties are named for saints than in any other state.
Counties by Year
- 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, Shasta, Solano, Sonoma, Sutter, Trinity, Tuolumne, Yola and Yuba Counties was the 27 original counties created as of February 18, 1850.
- Imperial County was the last county created on August 7, 1907.
County Size Facts
- San Francisco County (47 sq mi) is the largest county in California.
- San Bernardino County (20,062 sq mi) is the smallest county in California.
County Population Facts
- Alpine County (1,120) is the least populated county in California.
- Los Angeles County (10,163,507) is the most populated county in California.
California City Facts
California’s 10 largest (2010) cities are:
- Los Angeles (3,792,621) is in Los Angeles County
- San Diego (1,301,617) is in San Diego County
- San Jose (945,942) is in Santa Clara County
- San Francisco (805,235) is in San Francisco County
- Fresno (494,665) is in Fresno County
- Sacramento (466,488) is in Sacramento County
- Long Beach (462,257) is in Los Angeles County
- Oakland (390,724) is in Alameda County
- Bakersfield (347,483) is in Kern County
- Anaheim (336,265) is in Orange County
Boundary Changes of California Counties from 1850-1925
This Interactive Map of California Counties show the historical boundaries, names, organization, and attachments of every county, extinct county and unsuccessful county proposal from 1850 to 1925.
Many of the county boundaries have also experienced small changes over the years. The original county boundaries tended to follow the geography of the land, often being established along mountain ridges and similar natural features.
These days, many of those boundaries have been altered to run along either section lines or township lines.
List of California Counties
|County||Created||Created From||Named For||County Seat||Notes|
|Alameda County||25 Mar 1853||Contra Costa and Santa Clara Counties||The oak and other trees, once abundant in the region; alameda is Spanish for “avenue shaded by trees” or “cottonwood grove”.||Oakland|
|Alpine County||16 Mar 1864||Amador, El Dorado, Calaveras, Mono and Tuolumne Counties||Location high in the Sierra Nevada; alpine refers to the Alps or other mountains.||Markleeville|
|Amador County||01 May 1854||Calaveras County||Jose Maria Amador (1794–1883), a soldier, rancher, and miner who, along with several Native Americans, established a successful gold mining camp near present-day Amador City in 1848.||Jackson|
|Butte County||18 Feb 1850||Original County||Sutter Buttes, which were mistakenly thought to be in the county at the time of its establishment.||Oroville|
|Calaveras County||18 Jun 1850||Original County||Calaveras River; calaveras is Spanish for “skulls”.||San Andreas|
|Colusa County||18 Feb 1850||Original County||Rancho Colus land grant from Mexico.||Colusa|
|Contra Costa County||18 Feb 1850||Original County||Location across San Francisco Bay from San Francisco; contra costa is Spanish for “opposite coast”.||Martinez|
|Del Norte County||02 Jul 1857||Klamath County||Location along California’s northern border; del norte is Spanish for “northern”.||Crescent City|
|El Dorado County||18 Feb 1850||Original County||El Dorado, a mythical city of gold, owing to the area’s significance in the California Gold Rush.||Placerville|
|Fresno County||19 Apr 1856||Mariposa, Merced and Tulare Counties||The city of Fresno; fresno is Spanish for “ash tree”.||Fresno|
|Glenn County||05 May 1891||Colusa County||Dr. Hugh J. Glenn, a California businessman and politician.||Willows|
|Humboldt County||12 May 1853||Trinity County||Alexander von Humboldt, a German naturalist and explorer.||Eureka|
|Imperial County||06 Aug 1907||San Diego County||Imperial Valley, named after the Imperial Land Company.||El Centro|
|Inyo County||22 Mar 1866||Mono and Tulare Counties||Exact etymology disputed; early settlers believed Inyo to be the native name for area mountains, but it may be the name of a Mono Indian leader.||Independence|
|Kern County||02 Sep 1866||Los Angeles and Tulare Counties||Edward Kern, cartographer for John C. Fremont’s 1845 expedition.||Bakersfield|
|Kings County||22 Mar 1893||Tulare County||Kings River; original Spanish name Rio de los Santos Reyes (“River of the Holy Kings”).||Hanford|
|Lake County||20 Oct 2019||Napa County||Clear Lake.||Lakeport|
|Lassen County||01 Apr 1864||Plumas and Shasta Counties, and now defunct Lake County, Nevada||Peter Lassen, a Danish naturalist and explorer.||Susanville|
|Los Angeles County||18 Feb 1850||Original County||The city of Los Angeles, derived from the original Spanish name El Pueblo de Nuestra Señora la Reina de los Angeles del Río de Porciúncula (“The Village of Our Lady, the Queen of the Angels of the River of Porziuncola”).||Los Angeles|
|Madera County||11 Nov 1893||Mariposa County||The city of Madera, which was named for the forested landscape; madera is Spanish for “wood”.||Madera|
|Marin County||18 Feb 1850||Original County||Exact etymology disputed; probably a corrupted abbreviation of Bahía de Nuestra Señora del Rosario la Marina, the Spanish name for area headlands along San Francisco Bay.||San Rafael|
|Mariposa County||18 Feb 1850||Original County||The city of Mariposa; mariposa is Spanish for “butterfly”.||Mariposa|
|Mendocino County||18 Dec 0850||Original County||Antonio de Mendoza, first viceroy of New Spain.||Ukiah|
|Modoc County||19 Apr 1855||Mariposa County||The city of Merced, derived from the original Spanish name El Río de Nuestra Señora de la Merced (“River of Our Lady of Mercy”).||Merced|
|Mono County||17 Feb 0874||Siskiyou County||The Modoc people.||Alturas|
|Monterey County||24 Jan 1861||Calaveras, Fresno and Mariposa Counties||Mono Lake; derived from Monachi, a Yokut name for native peoples of the Sierra Nevada.||Bridgeport|
|Merced County||18 Feb 1850||Original County||Derived from Monterey Bay, which was named for a Viceroy of New Spain, Gaspar de Zúñiga, 5th Count of Monterrey.||Salinas|
|Napa County||18 Feb 1850||Original County||Disputed origin; possibly derived from the Patwin word napo, meaning “home”.||Napa|
|Nevada County||25 Feb 1851||Yuba County||The phrase Sierra Nevada; nevada is Spanish for “snow-covered,” referencing the area’s high elevation. The neighboring state was named after the county, which was named after Nevada City.||Nevada City|
|Orange County||11 Mar 1889||Los Angeles County||Oranges, which were widely cultivated in the area at the time the county was established.||Santa Ana|
|Placer County||25 Apr 1851||Sutter and Yuba Counties||California Gold Rush, a reference to the area being a center of the California Gold Rush.||Auburn|
|Plumas County||18 Mar 1854||Butte County||The Feather River; plumas is Spanish for “feathers”.||Quincy|
|Riverside County||11 Mar 1893||San Bernardino and San Diego Counties||The city of Riverside, named for its location on the Santa Ana River.||Riverside|
|Sacramento County||18 Feb 1850||Original County||The city of Sacramento, named after the Santisimo Sacramento (Spanish for “Most Holy Sacrament”).||Sacramento|
|San Benito County||12 Apr 1874||Monterey County||Saint Benedict (Benito is a Spanish diminutive of Benedict).||Hollister|
|San Bernardino County||26 Apr 1853||Los Angeles County||The city of San Bernardino, named after Saint Bernardino of Siena (Spanish for Saint Bernardine).||San Bernardino|
|San Diego County||18 Feb 1850||Original County||The city of San Diego, from Mission San Diego (Spanish for Saint Didacus).||San Diego|
|San Francisco County||18 May 1850||Original County||The city of San Francisco, from Presidio of San Francisco and Mission San Francisco de Asís, named after Saint Francis of Assisi (Spanish for Saint Francis).||San Francisco|
|San Joaquin County||18 Feb 1850||Original County||Spanish for Saint Joachim, father of the Virgin Mary.||Stockton|
|San Luis Obispo County||18 Feb 1850||Original County||The city of San Luis Obispo, from Mission San Luis Obispo, named after Saint Louis of Toulouse (Spanish for Saint Louis, the Bishop).||San Luis Obispo|
|San Mateo County||18 Jun 1856||San Francisco and Santa Cruz Counties||Spanish for Saint Matthew.||Redwood City|
|Santa Barbara County||18 Feb 1850||Original County||The city of Santa Barbara, from Mission Santa Barbara, (Spanish for Saint Barbara).||Santa Barbara|
|Santa Clara County||18 Feb 1850||Original County||City of Santa Clara, from Mission Santa Clara de Asís, named for Saint Clare of Assisi (Spanish for Saint Clare).||San Jose|
|Santa Cruz County||19 Jul 1850||Original County||The city of Santa Cruz, from Mission Santa Cruz(Spanish for “holy cross”).||Santa Cruz|
|Shasta County||18 Feb 1850||Original County||Mount Shasta; the indigenous Shasta people.||Redding|
|Sierra County||16 Feb 1852||Yuba County||Sierra is Spanish for “mountain range”, a reference to the area’s topography.||Downieville|
|Siskiyou County||22 Aug 1852||Shasta and Klamath Counties||Siskiyou Mountains; exact etymology of Siskiyou is disputed.||Yreka|
|Solano County||18 Feb 1850||Original County||Chief Solano of the Suisunes.||Fairfield|
|Sonoma County||18 Feb 0850||Original County||Exact etymology disputed; probably a Pomo term meaning “valley of the moon,” which references a native legend about spiritual activity in the area.||Santa Rosa|
|Stanislaus County||01 Sep 1854||Tuolumne County||Stanislaus River, named after Estanislao, a native of the area when California was under Spanish and Mexican rule.||Modesto|
|Sutter County||18 Feb 1850||Original County||John Sutter, a Swiss pioneer of California associated with the California Gold Rush.||Yuba City|
|Tehama County||09 Apr 1856||Butte, Colusa and Shasta Counties||The city of Tehama, probably a native term describing its location.||Red Bluff|
|Trinity County||18 Oct 1850||Original County||The city of Trinidad, Spanish for “trinity”.||Weaverville|
|Tulare County||20 Apr 1852||Mariposa County||Tulare Lake, which is named after the tule rush (Schoenoplectus acutus) that grew in the marshes and sloughs along its shores.||Visalia|
|Tuolumne County||18 Feb 1850||Original County||Exact etymology disputed; probably a corruption of the native term talmalamne, which means “cluster of stone wigwams,” a reference to local cave dwelling tribes.||Sonora|
|Ventura County||22 Nov 1872||Santa Barbara County||The city of Ventura, derived from Mission San Buenaventura (Spanish for St. Bonaventure).||Ventura|
|Yolo County||18 Feb 1850||Original County||The Yolan people, a local Native American tribe.||Woodland|
|Yuba County||18 Feb 1850||Original County||Named either by the Maidu people, a local Native American tribe who live on the banks of the Feather and Yuba Rivers, for one of their villages, or by Gabriel Moraga for the wild grapes (Vitis californica) that grow abundantly at the edge of the rivers (uva is Spanish for “grape”).||Marysville|
|Old Branciforte County (Extinct)||18 Feb 1850||California Lands||after the Spanish pueblo founded there in 1797||renamed Santa Cruz County, 19 April 1850|
|Old Buena Vista County (Proposed)||30 Apr 1855||Tulare County||16 Apr 1856, was a failed attempt to create a county from the territory of Tulare County, California between 1855 and 1859|
|Old Coso County (Proposed)||04 Apr 1864||Mono and Tulare Counties||creation did not take effect. The region was later organized in 1866 as Inyo County with additions from Los Angeles and San Bernardino counties.|
|Old Coloma County (Proposed)||was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to El Dorado County.|
|Old Frezno County (Extinct)||19 Apr 1856||Calaveras, Mariposa, Merced, Tulare, and Tuolumne Counties||by Apr 1862 the phonetic spelling of “FREZNO” changed to “FRESNO.”|
|Old Fremont County (Proposed)||county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to Yola County and later changed the name to Yolo County.|
|Old Klamath County (Extinct)||25 Apr 1851||Trinity County||Trinidad, In 1854 the county seat was moved to Crescent City. in 1856, the county seat was moved inland, to Orleans Bar, now Orleans.||Part of the county’s territory went to Del Norte County in 1857. On 30 May 1874 Klamath Countywas finally abolished, divided into Siskiyou and Humboldt counties.|
|Old Mount Diablo County (Proposed)||Mount Diablo County was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to Contra Costa County.|
|Nataqua Territory||26 Apr 1856||In March 1861, created the official Territory of Nevada|
|Old Oro County (Proposed)||Oro County was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to Tuolumne County.|
|Old Pautah County (Extinct)||03 May 1852||from Utah territory||the never-organized county was abolished by California on 8 April 1859|
|Old Redding County (Proposed)||Redding County was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to Shasta County.|
List of Old Former / Extinct California Counties
California contains some counties that no longer exist because they were discontinued, renamed or merged with another county. These are important for genealogy research purposes.
The below counties formerly within the area of the State of California no longer exist:
Branciforte County, California
Branciforte County was one of the original 27 counties adopted by statutes of 1850, but soon after that the legislature changed the name to Santa Cruz County.
Coloma County, California
Coloma County was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to El Dorado County.
Coso County, California
Coso County, however, was never organized. In 1866 substantially the same territory was created as Inyo County.
Fremont County, California
Was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to Yola County and later changed the name to Yolo County.
Coloma County, California
Mount Diablo County, California
Was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to Contra Costa County.
Oro County, California
Was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to Tuolumne County.
Coloma County, California
Created in 1852, an act to be effective when the United States Congress ceded to the State of California the territory described, in what is now the State of Nevada. The County seat was to be Carsonville. California never acquired the territory and the act creating the county was repealed in 1859.
Redding County, California
Was a county proposed by a committee of the California Constitutional Convention. Before the statute was adopted, the legislature changed the name to Shasta County.