In 2019, the US Undocumented Population Continued a Decade-Long Decline and the Foreign-Born Population Neared Zero Growth

This report presents new estimates of the undocumented population residing in the United States in July 2019, by country of origin and state of residence. The Center for Migration Studies (CMS) derived the estimates by analyzing data collected in the annual American Community Survey (ACS) conducted by the US Census Bureau (Ruggles et al. 2020 ). The methodology used to estimate the undocumented population is described in the Appendix.

The report highlights an aspect of population change — the number leaving the population — that is often overlooked in discussions of immigration trends. The report shows that the annual numbers leaving the population, especially through return migration to Mexico, have been the primary determinant of population change in the undocumented population in the past decade. Increasing numbers leaving the population have also led to near-zero growth of the total foreign-born population, which grew by just 20,000 from July 2018 to June 2019, the slowest growth in that population in more than a half century. Major findings include the following:

• The undocumented population continued to decline in 2019, falling by 215,000 compared to 2018; this population has declined by 1.4 million, or 12 percent, since 2010.

• The undocumented populations from Central America and Asia increased at the same rate from 2010 to 2016.

• After 2016, the population from Asia stopped growing, and the population from Central America increased by about 200,000.

• Since 2010, the undocumented population from Mexico has fallen from 6.6 million to 4.8 million, or by 28 percent.

• In 2019, 42 states and Washington, DC, had fewer undocumented residents from Mexico than they had in 2010.

• The states with increases in undocumented persons from Mexico had small undocumented populations.

• The undocumented population in California continued its decade-long decline, falling by 23 percent from 2.9 million in 2010 to 2.3 million in 2019.

• Annual arrival and departure data for Mexico show that the US Senate–passed comprehensive immigration reform bill, which provided for a large legalization program, did not increase undocumented immigration; instead, it seemed to reduce emigration from the United States.

• Net growth of the total foreign-born population fell to just 20,000 from July 2018 to June 2019. The drop occurred because the number leaving the population increased sharply after 2015.

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