California County Maps: Interactive History & Complete List

County map of California — Map of California county boundaries and county seats.

Maps of California are a crucial element of family history research, notably if you live far away from where your ancestor resided.

Due to the fact that California’s political borders have sometimes changed over the years, historic maps can be crucial in helping you uncover the precise location of your ancestor’s hometown, just what land they owned, who their neighbors were, and a lot more besides.

Maps of California are an excellent tool for starting out with your own research because they provide valuable information and facts right away and present them in a clear and easily understandable format.

California is bordered by Oregon, Nevada, and Arizona.

Learn more historical facts about California counties here.

Interactive Map of California County Formation History

AniMap Plus 3.0, with the permission of the Goldbug Company

List of Every California County

Alameda County

Located in the San Francisco Bay Area, Alameda County has a population of approximately 1.6 million. It was established in 1853.

Alpine County

With a population of around 1,100, Alpine County is the least populous county in California. It was established in 1864.

Amador County

Amador County is home to about 39,000 people and was founded in 1854. It is located in the Sierra Nevada region.

Butte County

Situated in the Sacramento Valley region, Butte County has a population of around 231,000. It was established in 1850.

Calaveras County

Calaveras County has approximately 45,000 residents and was founded in 1850. It is also located in the Sierra Nevada region.

Colusa County

Colusa County is situated in the Sacramento Valley region and has a population of around 22,000. It was established in 1850.

Contra Costa County

Contra Costa County was established in 1850 and is part of the San Francisco Bay Area. It is home to approximately 1.1 million people.

Del Norte County

Located on the coast in Northern California, Del Norte County has a population of around 28,000. It was established in 1857.

El Dorado County

El Dorado County is also situated in the Sierra Nevada region and has approximately 193,000 residents. It was founded in 1850.

Fresno County

Fresno County is located in the San Joaquin Valley region and has a population of around 1 million. It was established in 1856.

Glenn County

Located in the Sacramento Valley region, Glenn County has a population of around 28,000. It was founded in 1891.

Humboldt County

Situated on the coast in Northern California, Humboldt County is home to approximately 135,000 people. It was established in 1853.

Imperial County

Imperial County was founded in 1907 and is located in the southeastern part of California. It has a population of around 180,000 people.

Inyo County

Inyo County is located in the eastern part of California and has a population of around 18,000. It was established in 1866.

Kern County

Kern County is situated in the southern part of California and is home to around 900,000 people. It was founded in 1866.

Kings County

Located in the San Joaquin Valley region and established in 1893, Kings County has around 156,000 residents.

Lake County

Lake County is situated in the northern part of California and has a population of around 65,000. It was founded in 1861.

Lassen County

Lassen County is located in the northeastern part of California and has a population of around 31,000. It was established in 1864.

Los Angeles County

Los Angeles County is the most populous county in California, with a population of over 10 million people. It was founded in 1850.

Madera County

Madera County was established in 1893 and is located in the central part of California. It is home to around 157,000 people.

Marin County

Situated in the San Francisco Bay Area, Marin County has a population of around 259,000. It was established in 1850.

Mariposa County

Mariposa County is located in the central part of California and has around 18,000 residents. It was founded in 1850.

Mendocino County

Located on the coast in Northern California, Mendocino County has a population of around 88,000. It was established in 1850.

Merced County

Merced County is situated in the central part of California and was established in 1855. It has a population of around 287,000.

Modoc County

Modoc County is located in the northeastern part of California and is home to around 9,000 people. It was founded in 1874.

Mono County

Mono County was established in 1861 and is located in the eastern part of California. It has a population of around 14,000.

Monterey County

Situated on the central coast of California, Monterey County has around 438,000 residents. It was established in 1850.

Napa County

Napa County is located in the North Bay region of California and was founded in 1850. It has a population of around 138,000.

Nevada County

Nevada County is located in the Sierra Nevada region and is home to around 100,000 people. It was established in 1851.

Orange County

Orange County is situated in the southern part of California and has a population of around 3 million. It was founded in 1889.

Placer County

Placer County is located in the Sierra Nevada region and has around 408,000 residents. It was established in 1851.

Plumas County

Plumas County is located in the northeastern part of California and was founded in 1854. It has a population of around 18,000.

Riverside County

Riverside County is situated in the southern part of California and has a population of around 2.5 million. It was established in 1893.

Sacramento County

Sacramento County was established in 1850 and is located in the Sacramento Valley region. It is home to around 1.5 million people.

San Benito County

San Benito County is located in the central coast region of California and is home to around 63,000 people. It was founded in 1874.

San Bernardino County

San Bernardino County is situated in the southern part of California and has around 2.2 million residents. It was established in 1853.

San Diego County

San Diego County is located in the southern part of California and has a population of around 3.3 million. It was founded in 1850.

San Francisco County

San Francisco County is situated in the San Francisco Bay Area and was established in 1850. It has a population of around 883,000.

San Joaquin County

San Joaquin County was established in 1850 and is located in the Central Valley region. It has around 800,000 residents.

San Luis Obispo County

Located on the central coast of California, San Luis Obispo County has a population of around 284,000. It was established in 1850.

San Mateo County

San Mateo County is located in the San Francisco Bay Area and is home to around 770,000 people. It was established in 1856.

Santa Barbara County

Located on the central coast of California, Santa Barbara County has a population of around 450,000. It was founded in 1850.

Santa Clara County

Santa Clara County was established in 1850 and is located in the San Francisco Bay Area. It has around 2 million residents.

Santa Cruz County

Santa Cruz County is situated on the central coast of California and has a population of around 275,000. It was founded in 1850.

Shasta County

Shasta County is located in the northern part of California and was established in 1850. It is home to around 180,000 people.

Sierra County

Sierra County is situated in the northeastern part of California and has a population of around 3,000. It was founded in 1852.

Siskiyou County

Siskiyou County was established in 1852 and is located in the northern part of California. It is home to around 43,000 people.

Solano County

Solano County is located in the San Francisco Bay Area and has a population of around 450,000. It was established in 1850.

Sonoma County

Sonoma County is situated in the North Bay region of California and has a population of around 500,000. It was founded in 1850.

Stanislaus County

Stanislaus County was established in 1854 and is located in the Central Valley region. It has around 550,000 residents.

Sutter County

Sutter County is located in the Central Valley region and has a population of around 100,000. It was established in 1850.

Tehama County

Tehama County is located in the northern part of California and is home to around 65,000 people. It was founded in 1856.

Trinity County

Trinity County is located in the northeastern part of California and has a population of around 12,000 people. It was established in 1850.

Tulare County

Tulare County is situated in the Central Valley region and has around 466,000 residents. It was established in 1852.

Tuolumne County

Tuolumne County was founded in 1850 and is located in the Sierra Nevada region. It has a population of around 55,000 people.

Ventura County

Ventura County is located in the southern part of California and is home to around 850,000 people. It was established in 1872.

Yolo County

Yolo County was founded in 1850 and is situated in the Sacramento Valley region. It has a population of around 220,000.

Yuba County

Yuba County is located in the Central Valley region and has around 80,000 residents. It was established in 1850.

Old Antique Atlases & Maps of California

Disclaimer: All California maps are free to use for your own genealogical purposes and may not be reproduced for resale or distribution.

Source: David Rumsey Historical Map Collection

Map of California – 1845

1845 Atlas Map of the Californias
Map of California – 1856

1856 California Atlas Map
Map of California – 1866

1866 Map of the Public Surveys in California and Nevada
Map of California – 1880

1880 County map of the state of California (with) San Francisco, (with) San Francisco Bay and vicinity

California Map Links

About the author

Caleb Pike is an avid hiker and nature lover, with a passion for exploring the great outdoors. He's a writer, photographer, and adventurer, always seeking new trails to blaze and peaks to conquer.