About 2.3 million undocumented immigrants were living in California as of 2023, more than in any other state and roughly 16% of the estimated 14 million unauthorized residents nationwide.1Pew Research Center. Record 14 Million Unauthorized Immigrants Lived in the US in 2023 That works out to about 6% of California’s total population.2Public Policy Institute of California. Immigrants in California No government agency conducts a direct count, so every published figure is a statistical estimate and the true number could sit somewhat higher or lower.
Why the Number Is an Estimate
The U.S. Census Bureau does not ask about legal status. Its surveys collect citizenship, place of birth, and year of entry, but never whether a person has authorization to be in the country.3U.S. Census Bureau. Place of Birth, Citizenship, Year of Entry Unauthorized residents are still captured inside the total foreign-born population, because the surveys count everyone regardless of status.4U.S. Census Bureau. Frequently Asked Questions About Foreign-Born
Researchers arrive at an unauthorized count using what’s called the residual method. They start with the total foreign-born population from the American Community Survey, then subtract everyone whose legal status can be accounted for through administrative records: naturalized citizens, green card holders, refugees, visa holders, and other authorized categories. What’s left is treated as the unauthorized population.5Social Security Administration. Measuring the Number of Unauthorized Immigrants in the United States – A Review of the Residual Estimation Method
The Pew Research Center, the Migration Policy Institute, the Center for Migration Studies, and California’s own Public Policy Institute each publish estimates built on variations of this technique. Their assumptions about survey undercount, emigration, and mortality differ, which is why their numbers can vary by a few hundred thousand even when they describe the same year.
How the Population Has Changed Over Time
California’s undocumented population peaked at roughly 2.8 million around 2007, then fell sharply.2Public Policy Institute of California. Immigrants in California The 2008 housing crash eliminated construction and service jobs that had drawn many workers to the state, and federal border enforcement tightened at the same time. By the early 2010s the count had dropped to about 2.3 million and continued drifting downward through much of the decade.
After bottoming out in the late 2010s, the national unauthorized population began rising again through 2022 and 2023, and California’s count moved up with it. The current 2.3 million figure reflects a partial rebound from the low point but sits well below the 2007 peak.
The composition changed as much as the total. The number of undocumented immigrants from Mexico dropped substantially, driven partly by Mexico’s improving economy and partly by tighter border security. That decline was offset in part by growing arrivals from Guatemala, Honduras, and El Salvador, along with increasing numbers from Asian countries. California’s undocumented population today looks meaningfully different from the one of two decades ago, even though the headline total has settled back near where it stood in the early 2010s.
Where Undocumented Residents Live in California
Undocumented residents concentrate in metro areas where established immigrant communities, reachable housing, and available work overlap. Los Angeles County holds by far the largest share. Research from USC’s Equity Research Institute estimates roughly 900,000 undocumented residents in the county alone, about 9% of all LA County residents and a larger share of the working-age adult population.
The San Francisco Bay Area and the Inland Empire (Riverside and San Bernardino counties) form the next two clusters. The Bay Area draws workers into service, hospitality, and maintenance jobs tied to the tech economy. The Inland Empire pulls them into warehouse and logistics operations and into residential construction.
The Central Valley follows a different rhythm. Agricultural counties such as Fresno, Kern, and Tulare hold significant undocumented populations, but the numbers move with the growing seasons. Workers often travel between harvest regions or cross into neighboring states for seasonal work, so year-round estimates are less stable there than in the urban counties. The common thread is proximity to industries that rely on immigrant labor and neighborhoods where rent still fits a low-wage paycheck.
California’s Share of the National Total
The national unauthorized population reached a record 14 million in 2023, driven by two consecutive years of unusually high migration from countries other than Mexico.1Pew Research Center. Record 14 Million Unauthorized Immigrants Lived in the US in 2023 California’s 2.3 million represents about 16% of that total. In the early 1990s the state held roughly 40% of the national count, and in the mid-2000s about 23%.2Public Policy Institute of California. Immigrants in California
A shrinking share does not mean California has lost undocumented residents. Other destinations have grown faster. Texas, Florida, New York, New Jersey, and Illinois have all seen substantial increases as immigrants settle closer to jobs in meatpacking, construction, and service industries outside the traditional gateway states. California still has more undocumented residents than any other state by a wide margin, but the national map is far more dispersed than it was a generation ago.
The Workforce Behind the Number
Nearly 1.5 million undocumented residents participate in California’s labor force, accounting for almost 8% of all workers in the state.6Lieutenant Governor. New Report – Lt. Governor Kounalakis Highlights Immigrants Vital Role in Californias Economy The group skews younger than the general workforce and has an unusually high employment rate, because most came to California to work.
Agriculture is the sector most visibly dependent on this labor. An estimated 50% of California’s farmworkers lack legal authorization, reflecting decades of reliance on immigrant workers in the state’s $50-billion-plus farming industry.7Office of Governor Gavin Newsom. California Providing Free Legal Services for Undocumented Farmworkers Construction is the other large employer, with about 26% of construction laborers in California being undocumented.6Lieutenant Governor. New Report – Lt. Governor Kounalakis Highlights Immigrants Vital Role in Californias Economy Hospitality, food service, landscaping, and domestic work fill out the picture.
These workers pay into Social Security and state payroll systems through paycheck withholdings, often filing with Individual Taxpayer Identification Numbers because they cannot obtain Social Security numbers. A study by the Institute on Taxation and Economic Policy estimated that undocumented immigrants in California contributed $8.5 billion in state and local taxes in a single year, including sales taxes, property taxes paid through rent, and income taxes filed with ITINs.