What You Should Know About the US Undocumented and Eligible-to-Naturalize Populations
Center for Migration Studies of New York
August 4, 2021

The Center for Migration Studies of New York (CMS) has released its most recent estimates on the undocumented and eligible-to-naturalize immigrant populations in the United States. CMS estimates that 10.35 million undocumented immigrants and 8.1 million immigrants who are eligible to naturalize reside in the United States. The eligible-to-naturalize population is lawful permanent residents (LPRs), i.e. green card holders, who have resided in the United States for five years or more, served in the US military, or are married to a US citizen.
These estimates are based on data from the 2019 American Community Survey (ACS) conducted by the US Census Bureau. Because of the in-depth questions the ACS asks, CMS can derive detailed profiles of immigrant populations that provide estimates of country of origin, years of US residency, race/ethnicity, occupation, health insurance coverage, and more.*
Data tool users can conduct their own state and local queries of the size and characteristics of the US undocumented and eligible-to-naturalize populations at data.cmsny.org.
Key Findings about the US Undocumented and Eligible-to-Naturalize Populations
Undocumented immigrants have deep social, economic, and familial ties to the United States.
The percentage of undocumented immigrants that has lived in the United States for 15 years or more increased from 25 percent to 43 percent between 2010 and 2019. CMS also estimates:
- 38 percent of undocumented immigrants (3.9 million) are parents of US citizens,
- 16 percent are married to a US citizen or lawful permanent resident (LPR),
- 59 percent speak English well, very well, or only English, and
- 96 percent of those in the labor force are employed.
Additionally, 6.7 million US citizens share their household with an undocumented resident. Out of this group, 5.5 million are minors (under the age of 18). Undocumented immigrants have made the United States their home and, in the process, have become integral to US communities as long-term residents, workers, and family members.
Noncitizens, particularly the undocumented, face challenges because of their status.
While CMS data points to the tremendous contributions of immigrant noncitizens, including during the pandemic, it also highlights the challenges facing this community. For example, CMS estimates:
- 20 percent of the US undocumented population lives at or below the poverty threshold,
- 50 percent does not have health insurance,
- 40 percent has less than a high school diploma, and
- 14 percent does not speak English.
The eligible-to-naturalize population fares better than the undocumented. CMS estimates:
- 15 percent of the eligible-to-naturalize population lives at or below the poverty threshold,
- 17 percent does not have health insurance,
- 34 percent has less than a high school diploma, and
- 13 percent does not speak English.
Expanding legal pathways and promoting citizenship could address these disparities. A recent CMS report, Making Citizenship an Organizing Principle of the US Immigration System: An Analysis of How and Why to Broaden Access to Permanent Residence and Naturalization for New Americans, found that the median household income was $25,800, or 27 percent, higher for the naturalized population, compared to the population that had not naturalized. When immigrants gain more secure and permanent legal status, their contributions to their families, communities, and the United States at large increase.
The undocumented population is shrinking.
An estimated 10.35 million undocumented immigrants resided in the United States in 2019 compared to 11.73 million in 2010. Thus, between 2010 and 2019, the undocumented population in the United States declined by 1.4 million, or 12 percent.
This demographic trend is primarily driven by Mexican nationals voluntarily leaving the United States. Since 2010, the undocumented population from Mexico has fallen from 6.6 million to 4.8 million, or by 28 percent.
The undocumented population from Central America increased by 395,000 and from Asia by 165,000. However, growth in the Asian undocumented population has slowed in recent years, particularly China, Korea, the Philippines, and Vietnam whose immigrant populations decreased.
The fact that the US undocumented population is shrinking provides important context to media and political narratives, which often emphasize short-term “crises” or claim that the United States is “overwhelmed” by immigrants.
Additional Resources
Since the launch of its Democratizing Data Initiative in 2013, CMS has provided expert analysis of its estimates of the US undocumented and eligible-to-naturalize populations in numerous publications. These publications have considered:
- The decline in the US undocumented population since 2010
- The importance of expanding pathways to lawful permanent residence and citizenship
- The contributions of immigrant essential workers during the COVID-19 pandemic
- The trend of Mexican nationals returning to Mexico
- The integration and contributions of DACA recipients
- The fact that new arrivals to the US undocumented population primarily overstay visas rather than enter without inspection
- The family-based immigration visa backlog
- TPS recipients from El Salvador, Honduras, and Haiti
- The immense cost of deportations for families and US communities
To access CMS estimates at the national, state, and sub-state level, please visit data.cmsny.org.
*For a detailed description of the methodology CMS uses to derive these estimates and profiles, see the Appendix of “In 2019, the US Undocumented Population Continued a Decade-Long Decline and the Foreign-Born Population Neared Zero Growth” (Warren 2020).
August 4, 2021