Data / Rankings / Foreign-born population share / Counties in California

Counties in California by foreign-born share of the population

Santa Clara County had the highest foreign-born share of the population of 58 counties in 2021, at 39.9%. Sierra County had the lowest, at 3.3%. The median was 18.8% and the figure for California was 26.5%. Source: the U.S. Census Bureau.

Highest39.9Santa Clara County
Lowest3.3Sierra County
Median18.858 counties
California26.5History

All counties, 2021

CSVChart (SVG)

Santa Clara CountySanta Clara County: 39.9 %39.9San Mateo CountySan Mateo County: 35.1 %35.1San Francisco CountySan Francisco County: 34.1 %34.1Los Angeles CountyLos Angeles County: 33.5 %33.5Alameda CountyAlameda County: 32.9 %32.9Imperial CountyImperial County: 29.9 %29.9Orange CountyOrange County: 29.5 %29.5Monterey CountyMonterey County: 29 %29Colusa CountyColusa County: 26.7 %26.7Merced CountyMerced County: 26 %26Contra Costa CountyContra Costa County: 25 %25San Joaquin CountySan Joaquin County: 23.3 %23.3San Diego CountySan Diego County: 22.7 %22.7Santa Barbara CountySanta Barbara County: 22.4 %22.4Yolo CountyYolo County: 22.4 %22.4Sutter CountySutter County: 21.8 %21.8Tulare CountyTulare County: 21.7 %21.7Riverside CountyRiverside County: 21.5 %21.5Napa CountyNapa County: 21.5 %21.5Ventura CountyVentura County: 21.1 %21.1Sacramento CountySacramento County: 21 %21San Bernardino CountySan Bernardino County: 20.7 %20.7Stanislaus CountyStanislaus County: 20.1 %20.1San Benito CountySan Benito County: 20 %20Madera CountyMadera County: 19.9 %19.9Fresno CountyFresno County: 19.9 %19.9Solano CountySolano County: 19.7 %19.7Kern CountyKern County: 19.7 %19.7Kings CountyKings County: 19.1 %19.1Marin CountyMarin County: 18.5 %18.5Santa Cruz CountySanta Cruz County: 17.8 %17.8Mono CountyMono County: 16.8 %16.8Sonoma CountySonoma County: 16.3 %16.3Glenn CountyGlenn County: 16.1 %16.1Yuba CountyYuba County: 12.8 %12.8Mendocino CountyMendocino County: 12.3 %12.3Placer CountyPlacer County: 11.7 %11.7San Luis Obispo CountySan Luis Obispo County: 9.7 %9.7El Dorado CountyEl Dorado County: 9.3 %9.3Lake CountyLake County: 8.9 %8.9Tehama CountyTehama County: 8.5 %8.5Del Norte CountyDel Norte County: 8.2 %8.2Trinity CountyTrinity County: 7.8 %7.8Butte CountyButte County: 7.6 %7.6Modoc CountyModoc County: 7.2 %7.2Inyo CountyInyo County: 7.1 %7.1Amador CountyAmador County: 6.3 %6.3Nevada CountyNevada County: 6.1 %6.1Humboldt CountyHumboldt County: 6.1 %6.1Siskiyou CountySiskiyou County: 5.8 %5.8Mariposa CountyMariposa County: 5.6 %5.6Shasta CountyShasta County: 5.6 %5.6Lassen CountyLassen County: 5.4 %5.4Tuolumne CountyTuolumne County: 5.3 %5.3Alpine CountyAlpine County: 4.8 %4.8Calaveras CountyCalaveras County: 4.8 %4.8Plumas CountyPlumas County: 3.7 %3.7Sierra CountySierra County: 3.3 %3.3
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-09.

Full ranking

RankCounties2021 (%)
1Santa Clara County39.9
2San Mateo County35.1
3San Francisco County34.1
4Los Angeles County33.5
5Alameda County32.9
6Imperial County29.9
7Orange County29.5
8Monterey County29
9Colusa County26.7
10Merced County26
11Contra Costa County25
12San Joaquin County23.3
13San Diego County22.7
14Santa Barbara County22.4
15Yolo County22.4
16Sutter County21.8
17Tulare County21.7
18Riverside County21.5
19Napa County21.5
20Ventura County21.1
21Sacramento County21
22San Bernardino County20.7
23Stanislaus County20.1
24San Benito County20
25Madera County19.9
26Fresno County19.9
27Solano County19.7
28Kern County19.7
29Kings County19.1
30Marin County18.5
31Santa Cruz County17.8
32Mono County16.8
33Sonoma County16.3
34Glenn County16.1
35Yuba County12.8
36Mendocino County12.3
37Placer County11.7
38San Luis Obispo County9.7
39El Dorado County9.3
40Lake County8.9
41Tehama County8.5
42Del Norte County8.2
43Trinity County7.8
44Butte County7.6
45Modoc County7.2
46Inyo County7.1
47Amador County6.3
48Nevada County6.1
49Humboldt County6.1
50Siskiyou County5.8
51Mariposa County5.6
52Shasta County5.6
53Lassen County5.4
54Tuolumne County5.3
55Alpine County4.8
56Calaveras County4.8
57Plumas County3.7
58Sierra County3.3

Other periods

About this ranking

People who were not US citizens at birth, as a percentage of the total population. Includes naturalized citizens, lawful permanent residents, temporary migrants and unauthorized immigrants. United States: American Community Survey five-year estimate, where the period shown is the last year of the five-year span.

Based on place of birth, not nationality: a naturalized citizen counts as foreign born, and people born in Puerto Rico, the US island areas or abroad to American parents count as native. Not comparable with foreign_population_share, which counts foreign nationals in Spain and the EU. Calculated from counts in ACS table B05002, which are stored as inputs.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. Equal values share a rank.

How to cite

U.S. Census Bureau. American Community Survey 5-year estimates, table B05002: foreign-born population as a percentage of the total population, calculated with stored inputs. https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b05002.dat. Retrieved 2026-10-09.

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Questions

Which county has the highest foreign-born share of the population?

Santa Clara County, with 39.9% in 2021, according to the U.S. Census Bureau.

Which county has the lowest foreign-born share of the population?

Sierra County, with 3.3% in 2021.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Census Bureau, American Community Survey 5-year estimates, table B05002: foreign-born population as a percentage of the total population, calculated with stored inputs. Retrieved 2026-10-09.

Foreign-born population share: other rankings

Counties in California: more rankings