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Unauthorized Immigration

America is a nation of immigrants. Virtually all of us can trace our ancestry to people who immigrated to the United States. Even so, immigration is a controversial issue, particularly in the case of unauthorized immigration, where individuals enter or reside in the United States in violation of the law. How many individuals in the United States are unauthorized? Does unauthorized immigration have negative consequences, such as an increase in crime?

This brief focuses on unauthorized immigration; there are links in the Further Reading section to other immigration-related topics such as Authorized Immigration, Refugees and Asylum, and Border Security.

How large is the unauthorized population in the United States?  

Immigrants to the United States are either authorized immigrants or unauthorized immigrants. Authorized immigrants are those who hold a visa or refugee status that allows legal residence. Unauthorized individuals either enter without these documents or remain in the country after their travel visa has expired. A third category is individuals who have applied for asylum – while their case is being decided (which can take years), they are generally paroled to stay in the U.S.  

As of 2018, estimates of the unauthorized population in the U.S. amount to about 11 million individuals (see figure below). This total was about 23% of the total foreign-born population (people born outside the US but currently living in the country). The other 77% of the foreign-born population comprises authorized immigrants, including temporary visa holders, legal permanent residents (green card holders), and naturalized citizens.

As of late 2023, calculations based on available data by Policy vs Politics analysts show there are about 16 million individuals in the US who are either undocumented, have applied for refugee status but have not had their claims adjudicated, or were recently admitted as refugees. As the figures below show, this total is substantially higher than in 2018, when the last available official estimates were released by the Department of Homeland Security (DHS) and other credible private sources.  

For our 2023 estimate, Policy vs Politics analysts used the average of the 2018 estimates as a baseline, subtracting the DHS estimate of the number of undocumented who left the US during 2018 – 2023 and adding (a) the DHS estimate of the number of new illegal entrants during 2018 – 2023, (b) the number of refugees admitted in the same time, and (c) the number of individuals in the US who have asylum claims pending as of late 2023. It is important to recognize that people in the last two categories (refugees and those with pending claims) are in the US legally.  However, these large numbers undoubtedly contribute to public perceptions of the size of the undocumented population. As the figure shows, some of the 2018 unauthorized immigrants left by 2023 – but this decrease is more than offset by increases in the other categories.

Because of the increase in those with refugee status, pending asylum, or who have entered the U. S. illegally, the percentage of the U. S. population that is undocumented or resident pending an asylum application has significantly increased in recent years after being more-or-less constant since 2000. This trend is shown in the figure below, which adds the Policy vs Politics 2023 estimate to Pew Research Center data for 1990 – 2017.

Who are the “Dreamers?”

About 5% (580,000) of the unauthorized population are individuals brought to the United States as children by their parents. These individuals are referred to as Dreamers and are treated differently than other unauthorized immigrants. The Deferred Action for Childhood Arrivals program (DACA) allows these individuals to obtain temporary social security numbers, resident status, and work permits for two-year renewable intervals. DACA was created by a Presidential order in 2012, and a future President could end the program. Individuals eligible for DACA are those who entered the United States before they turned 16 and were under 31 years of age as of 2012. In some states, DACA recipients can attend state colleges and universities and pay in-state tuition rates. However, DACA recipients are not eligible for Medicaid or SNAP (Supplemental Nutrition Assistance Program or food stamps) benefits.

Where do unauthorized migrants come from?

Unauthorized immigrants come from around the world. After World War II, many unauthorized immigrants came from Western and Eastern Europe. Estimates place the majority of current arrivals – about 70% – arriving from Mexico and Central America, including El Salvador, Guatemala, Honduras and Venezuela. About 15% of unauthorized immigrants come from Asia, mostly from India, China, and the Philippines. For more details on these trends, see our policy brief on Border Security.

Can unauthorized migrants gain legal residency in the US?

Most unauthorized immigrants would prefer to obtain authorized status because that enables them to work legally and live without fear of deportation. Legal status also enables them to apply for U.S. citizenship. People who have entered the country without permission or overstayed their visas are not eligible to become legal permanent residents. Historically, some unauthorized immigrants are granted permanent resident status through the asylum or refugee process, but these numbers are small compared to the undocumented population. It is unclear whether this pattern will change, given the recent spike in asylum claims.  

What are the economic and social consequences of unauthorized migration?

One common concern about unauthorized immigration is that unauthorized immigrants take jobs and other resources away from American citizens. A related concern is that the presence of unauthorized immigrants may contribute to crime, or alter the culture and values of the US. These concerns have been researched by reputable social scientists (see the Source section for cites), reaching the following conclusions:

  1. Labor force participation among unauthorized immigrants is higher than that of both permanent residents and native-born citizens. Unauthorized immigrants generally fill jobs Americans do not want, such as seasonal or low-paying jobs in agriculture and service industries.
  2. Several studies have found that unauthorized immigrants had lower crime rates compared to American citizens and authorized immigrants and that communities with large immigrant populations had lower crime rates compared to communities with fewer immigrants. Notwithstanding these findings, it is clear that some individuals who cross the border without permission are doing so to engage in criminal activity, such as the importation of illegal drugs, including fentanyl. For additional details, see our policy brief on Border Security cited in the Further Reading section.
  3. The Personal Responsibility and Work Opportunity Reconciliation Act (PRWORA) of 1996 excludes most legal permanent residents and unauthorized immigrants from federal, state, and local social welfare programs. As a result, unauthorized immigrants are not eligible for most benefits, including welfare and Medicaid. However, because many unauthorized immigrants pay into Social Security as a condition of employment (using fake Social Security numbers) but are ineligible for benefits, they contribute to the fiscal health of the program.
  4. Local schools cannot deny unauthorized immigrant youth enrollment in public schools. Research shows state and local governments are most fiscally impacted by high levels of unauthorized immigration, as public schools are organized and funded at the state and local levels. Depending on housing arrangements, undocumented immigrants may or may not pay property taxes, which comprise a large portion of school funding. For example, in September 2023, estimates were that out of 800,000 elementary and secondary students in New York City, 20,000 were undocumented.  
  5. New York City uniquely has a ‘right to shelter’ mandate, which specifies that the city must provide shelter to anyone who asks for it. This has notably strained city resources as it has provided shelters for Venezuelan and other migrants in the city seeking asylum – who have recently been given special status to apply for work authorization.


Further Reading

Capps, R., Gelatt, J., Ruiz Soto, A. G., & Van Hook, J. (2020). Unauthorized Immigrants in the United States: Stable Numbers, Changing Origin. Migration Policy Institute,, accessed 5/24/23.

Kolker, A. F., & Straut-Eppsteiner, H. (2022). Unauthorized Immigrants: Frequently Asked Questions. Congressional Research Service., accessed 5/24/23.

Policy vs Politics Policy Brief: Authorized Immigration:

Policy vs Politics Policy Brief: Refugees and Asylum:

Policy vs Politics Policy Brief: Border Security (TBD)


How large is the unauthorized population in the United States?  

Lopez, M. H., Passel J. S., & Cohn, D. (2021). Key Facts About the Changing U.S. Unauthorized Immigrant Population. Pew Research Center,, accessed 5/23/23

United States Census (2021). Historical Population Change Date. , accessed 5/23/23

Capps, R., Gelatt, J., Ruiz Soto, A. G., & Van Hook, J. (2020). Unauthorized Immigrants in the United States: Stable Numbers, Changing Origin. Migration Policy Institute,, accessed 5/24/23.

U.S. Immigration and Naturalization Service (2005) Estimates of the Unauthorized Immigrant Population Residing in the United States: 1990 to 2000.  Department of Homeland Security,, accessed 6/22/23.

Department of Homeland Security. 2023.  Border Security Metrics Report: 2022., accessed 12/3/23

UNHCR.  2023.  Mid-Year Trends 2023., accessed 12/3/23

TRAC: Immigration.  2022. A Sober Assessment of the Growing U.S. Asylum Backlog., accessed 12/3/23.

Who are the “Dreamers”?

Gonzales, R. G., Terriquez, V., & Ruszczyk, S. P. (2014). Becoming DACAmented: Assessing the Short-Term Benefits of Deferred Action for Childhood Arrivals (DACA). American Behavioral Scientist, 58(14), 1852-1872.  

USCIS (2022)  “Active DACA Recipients.” United States Citizenship and Immigration Services., accessed 6/1/23

Kaiser Family Foundation. (2023). Key Facts on Deferred Action for Childhood Arrivals (DACA)., accessed 7/1/23.

Can Unauthorized Migrants Gain Legal Residency In The US?

Kolker, A. F., & Straut-Eppsteiner, H. (2022, August 10). Unauthorized Immigrants: Frequently Asked Questions. Congressional Research Service. May 24, 2023, 

What are the economic and social consequences of unauthorized immigration?

Kolker, A. F., & Straut-Eppsteiner, H. (2022). Unauthorized Immigrants: Frequently Asked Questions. Congressional Research Service., accessed 5/24/23.

Light, M. T., Hea, J., & Robey, J. P. (2020). Comparing Crime Rates Between Undocumented Immigrants, Legal Immigrants, and Native-born US Citizens in Texas. Proceedings of the National Academy of Sciences, 117(51), 32340-32347.

Ousey, G. C., & Kubrin, C. E. (2018). Immigration and Crime: Assessing a Contentious Issue. Annual Review of Criminology, 1(1), 63–84.

Jones, N., Marks, R., Ramirez, R., & Ríos-Vargas, M. (2021, August 12). Improved Race and Ethnicity Measures Reveal U.S. Population Is Much More Multiracial. United States Census Bureau,, accessed 6/1/23

Citrin, J., Lerman, A., Murakami, M., & Pearson, K. (2007). Testing Huntington: Is Hispanic Immigration a Threat to American Identity? Perspectives on Politics, 5(1), 31-48.

New York City Department of Homeless Services (2023).  History., accessed 12/3/23

Fitzsimmons, E.  2023.  New York City Moves To Suspend Right-To Shelter-Mandate.  The New York Times, October 3, 2023., accessed 12/3/23

Calkvan, B, Bumsted, R., and Spagat, E.  2023.  Influx of Migranrts tests Preparedness of NYC Schools.  AP, September 3, 2023,, accessed 12/4/23

This policy brief was researched in July 2023 by Policy vs Politic interns Mary Stafford and Zul Norin, drafted by Griffin Reid, and edited by Dr. Nicholas Clark and Dr. William Bianco, with the assistance of subject matter expert Dr. Alexandra Filindra.




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