This report presents estimates of the number of unauthorized immigrants in the United States as of July 2023 and for previous years back to 1990. These estimates supersede all previously published Pew Research Center estimates. Although this report draws largely on U.S. Census Bureau surveys, our estimates generally will not agree exactly with data published by the bureau because we include adjustments for survey omissions and corrections for various types of survey errors and anomalies.
The methods used to produce the estimates of the unauthorized immigrant population and its characteristics are described below (Methodology A). Two other methodology sections describe other parts of the report’s methodology. The second (Methodology B) describes the principal data sources used to produce the estimates and modifications made to the underlying surveys. The third section (Methodology C) provides details on how the estimates are rounded and definitions of various concepts used in the report.
Overview
The estimates for the U.S. unauthorized immigrant population presented in this report are based on a residual estimation methodology that compares a demographic estimate of the number of immigrants residing legally in the country with the total number of immigrants as measured by either the American Community Survey (ACS) or the Annual Social and Economic Supplement (ASEC) to the March Current Population Survey (CPS). The difference is the estimated number of unauthorized immigrants in the survey, a figure that later is adjusted for omissions from the survey (read below). The basic estimate is calculated as:
The lawful resident immigrant population is estimated by applying demographic methods to counts of lawful admissions covering the period since 1980 obtained from the Department of Homeland Security’s Office of Homeland Security Statistics and its predecessors, the DHS Office of Immigration Statistics and the Immigration and Naturalization Service, with projections to current years, when necessary.
Initial estimates are calculated separately for age-gender groups in six states (California, Florida, Illinois, New Jersey, New York and Texas) and the balance of the country; within these areas, the estimates are further subdivided into immigrant populations from 35 countries or groups of countries by period of arrival in the United States. Variants of the residual method have been widely used and are generally accepted as the best current estimates (e.g., DHS, Migration Policy Institute, Center for Migration Studies of New York, and earlier work at the Center).
The overall estimates for unauthorized immigrants build on these residuals by adjusting for survey omissions in these six states and the balance of the country, subdivided for Mexican immigrants and other groups of immigrants (remainder of Latin America, South and East Asia, and rest of world), depending on sample size and state.
Once the residual estimates have been produced, individual foreign-born respondents in the survey are assigned a specific status (one option being unauthorized immigrant) based on the individual’s demographic, social, economic, geographic and family characteristics in numbers that agree with the initial residual estimates for the estimated lawful immigrant and unauthorized immigrant populations in the survey. These status assignments are the basis for most characteristics reported (including, for example, specific countries of birth, detailed state estimates, period of arrival and household-family relationships). A last step in the weighting-estimation process involves developing state-level estimates that account for trends over time in the estimates.
Since the estimates are ultimately based on Census Bureau surveys, the unauthorized immigrant estimate and other population groups represent the number in the country as of the date of the survey. The reference date for the ACS is July 1 for the year of the survey; for the CPS-ASEC, it is March 1 for the survey year. Thus, our unauthorized immigrant population estimates for 2005-2023 represent the number in the country as of July 1 of each year.7 The 1995-2003 estimates are the number of unauthorized immigrants as of March 1. The 1990 estimates are for Census Day, or April 1, 1990.
Lawful immigrant population
The estimate of the lawful immigrant population (“L” in the estimation equation) is based on official counts of immigrant and refugee admissions. The principal source for the data is the Yearbook of Immigration Statistics published by DHS and its predecessor, the Immigration and Naturalization Service. The main groups of lawful immigrants arriving are:
- Lawful permanent residents (LPR or green card holders)
- New arrivals: This group is counted as arriving in the year they acquire their green card.
- Adjustments of status: These immigrants are already in the U.S. but have some status other than LPR. They are counted as lawful immigrants only as of the year they acquire their green card but their “year of arrival” is adjusted to an earlier date based on when they first arrived in the U.S.
- Some LPRs adjusting status have already been counted as lawful immigrants on arriving in the U.S. (e.g., refugees noted below), so they are not added when they adjust status to avoid double-counting them.
- Refugees: These immigrants, admitted from abroad because of humanitarian concerns in their home country, are counted as lawful immigrants in their year of admission. Virtually all refugees eventually become LPRs. When they “adjust status” to LPR, they are not counted again.
- Asylees: These immigrants, already in the U.S. when they are granted asylum for humanitarian concerns, are also counted as lawful immigrants in their year of admission. They are excluded from the LPR count when they adjust status.
- Former unauthorized immigrants granted legal residence under the 1986 Immigration Reform and Control Act: These immigrants were counted as lawful immigrants when their applications were approved, mainly in the late 1980s. They are overwhelmingly Mexican, and most entered the U.S. before 1980. They are not counted when they adjust status to LPR, but virtually all of them became LPRs before 2000.
Published tables for the DHS Yearbook of Immigration Statistics and some related sources provide the basic data for these groups. The data for arrivals is subdivided by country or region of birth, year or period of arrival, age, sex and state of residence.
For each year, the previous year’s population estimate is updated with estimates of mortality and emigration before the new cohort of LPRs is added to get the new population estimate for the lawful immigrant population by age, sex, country of birth, period of arrival and state.
Comparability with previous estimates
The estimates presented here for 1990-2023 are internally consistent and comparable across years and states. The estimates presented in this report supersede all previously published Pew Research Center estimates, especially estimates for the same dates using different data. (Read this methodology from 2018 for a more detailed description of earlier published estimates.)
The estimates in this report use survey data consistent with the censuses of 1990, 2000, 2010 and 2020. For the 2023 estimates and revised 2022 estimates, modifications to the surveys were necessary to bring the data in line with Census Bureau revisions of data for the population and net international migration since 2021. For the 1995-2009 surveys, special weights were developed to align with both the preceding and subsequent censuses. (Read Methodology B for more details.) As such, population figures for these years are not identical to those published from the original surveys.
Status assignments: Lawful and unauthorized immigrants
Individual survey respondents are assigned a status as a lawful or unauthorized immigrant based on the individual’s demographic, social, economic and geographic characteristics so that the resulting number of immigrants in various categories agrees with the totals from the residual estimates. The assignment procedure employs a variety of methods, assumptions and data sources.
First, all immigrants entering the U.S. before 1982 are assumed to be lawful immigrants. Then, the ACS and CPS data are corrected for known overreporting of naturalized citizenship on the part of recently arrived immigrants. Specifically, immigrants who have been in the U.S. for less than six years are not eligible to naturalize unless they are married to a U.S. citizen, in which case they can naturalize after three years. Immigrants reporting as naturalized who fail to meet these requirements are moved into the noncitizen category. All remaining naturalized citizens from countries other than Mexico and those in Central America are assigned as lawful immigrants because reporting of citizenship for these groups has been found to be largely accurate in the aggregate.8 Mexican and Central American immigrants who report being naturalized U.S. citizens are treated the same as noncitizens in the status assignment process. This means that some may be assigned as unauthorized immigrants; the rest remain as naturalized citizens.
Persons entering the U.S. as refugees are identified based on country of birth and year of immigration to align with known admissions of refugees and asylees (i.e., persons granted asylum). Then, individuals holding certain kinds of temporary visas are identified in the survey and each is assigned a specific lawful temporary migration status using information on country of birth, date of entry, occupation, education and certain family characteristics. The specific visa types identified:
- Foreign students (F, M visa)
- Visiting scholars (J visa)
- Physicians (J visa)
- Registered nurses (H-1A visas)
- Intracompany transfers (L visas)
- “High-tech” guest workers (H-1B visas)
- Diplomats and embassy employees (A visa)
- International organizations (G visas)
- Religious workers (R visas)
- Exchange visitors (J visas)
- Athletes, artists and entertainers (O, P visas)
- Spouses and children within these various categories
Finally, immigrants are screened on the basis of occupations, participation in public programs and family relationships with U.S.-born individuals and lawful immigrants. Some individuals are assigned as lawful immigrants on the basis of these characteristics:
- Refugees and naturalized citizens
- Lawful temporary immigrants
- Persons working for the government or the armed forces
- Veterans or active-duty members of the armed forces, military reserves or National Guard
- Participants in government programs not open to unauthorized immigrants: Supplemental Security Income (SSI), Temporary Assistance for Needy Families (TANF), Medicare, Medicaid and food stamps (Supplemental Nutrition Assistance Program, or SNAP)
- Persons entering the U.S. before 1982
- Persons with certain occupations that require lawful status or government licensing (e.g., police officers and other law enforcement occupations, lawyers, health care professionals)
- Children of citizens and lawful temporary migrants
- Most immediate relatives of U.S. citizens, especially spouses
- Other family members, especially those entering the U.S. before lawful residents
As a result of these steps, the foreign-born population is divided between individuals with “definitely lawful” status (such as long-term residents, naturalized citizens, refugees and asylees, lawful temporary migrants, and some lawful permanent residents) and a group of “potentially unauthorized” migrants. (Additional details can be found here.)
Cuban immigrants have required special treatment in the status assignments. Before 2017, virtually all Cubans entering the U.S. are lawful residents, even if they are not assigned refugee status, because they are treated differently from other arrivals based on the Cuban Adjustment Act of 1966. Early versions of the estimates failed to recognize this special status; revised estimates for 1995-2012 correct this oversight. The Obama administration in January 2017 changed policy to treat Cubans the same as other unauthorized entrants. Our estimates for 2018 and later no longer treat Cubans entering the U.S. in 2017 and later differently from other immigrants in the status assignment process.
The number of potentially unauthorized immigrants typically exceeds the estimated number of unauthorized immigrants from the residual estimates by 20%-35% nationally. So, to have a result consistent with the residual estimate of lawful and unauthorized immigrants, probabilistic methods are employed to assign lawful or unauthorized status to these potentially unauthorized individuals. The base probability for each assignment is the ratio of the residual estimate to the number of potentially unauthorized immigrants. These initial probabilities are first adjusted separately for parents living with their children and all others to ensure that an appropriate number of unauthorized immigrant children are selected and then by broad occupation categories.
After this last step in the probabilistic assignment process, there is a check to ensure that the statuses of family members are consistent; for example, all family members entering the country at the same time are assumed to have the same status. The resulting populations for unauthorized immigrants are compared with the residual estimates; if they disagree, the assignment probabilities are adjusted and the random assignments are repeated. The entire process requires several iterations to produce estimates that agree with the demographically derived population totals.
At the end, the final estimates agree with the residual estimates for the six individual states noted earlier and for the balance of the country; for lawful and unauthorized immigrants in each area born in Mexico, Latin America, Asia and the rest of the world (subject to sample size considerations); and for children and for working-age men and women within each category. Finally, the survey weights for the foreign born are adjusted upward for survey omissions (undercount) so the tabulated figures agree with the adjusted analytic, demographic estimates of the total number of lawful immigrants and unauthorized migrants developed in the very first step.
The result of the estimation/status assignment process is a dataset (ACS or CPS) in which each immigrant is assigned a legal status and survey weight that has been adjusted so that the immigrant population agrees with estimated totals for various status groups, regions of birth and states. After a final adjustment to align with state trends, this dataset is used for the estimates published in this report – for specific countries of birth, states, families, and various social and economic characteristics.
State estimates
The initial estimates of unauthorized immigrants for states other than the six largest (California, Texas, Florida, New York, Illinois and New Jersey) arise from the tabulated totals of the individual microdata records assigned as unauthorized immigrants. The overall trends at the state level are assumed to progress somewhat smoothly from one year to the next, though the initial estimates based on status assignments may not behave in exactly that way. Accordingly, the final estimated state totals for any given year take into account estimates for surrounding years; however, only a small number of state estimates generally require significant adjustment based on the trend analysis.
The last step in developing the individual weights for the unauthorized immigrants involves adjusting the initial weights in each state to agree with the totals from the trend analysis. The largest adjustments are in those states where the trend analysis showed a substantial difference between the initial estimates and the trend analysis. Nonetheless, all states are adjusted so that the state totals agree as closely as possible with either the initial estimate or the trend-based estimate. At the same time, the adjustment is done so that the national totals of the state populations agree with the residual estimates for the total unauthorized immigrant population and the totals from each of the four broad regions of birth.
Margins of error
Estimates of the unauthorized immigrant population are computed as the difference between a deterministic, administratively based estimate (i.e., the lawful foreign-born population, or “L” in the equation above) and a sample-based estimate (i.e., the survey total of the foreign-born population, or “S”). Consequently, the margin of error (or variance) for the estimated unauthorized population is the margin of error for “S,” the sample-based estimate of the foreign-born population. Thus, the margins of error are generally based on the variance of the foreign-born population entering since 1982.
For all years of the ACS, variances are computed with replicate weights supplied by the U.S. Census Bureau through IPUMS; for earlier CPS data, generalized variance formulas supplied in Census Bureau documentation were used to compute margins of error.
The ranges reported represent a 90% confidence interval around the estimates. They represent the sampling error associated with the survey-based estimate. Other sources of potential error – including the variability associated with the random assignment of statuses, potential errors in the status assignment process and non-sampling error in the surveys – are not represented in the reported margins of error. For this report, statistical tests rely on a 90% confidence level.
