2021 Update: How Many Illegal Aliens Live in the United States?
A FAIR Research Report | April 2022
As of the end of 2021, FAIR estimates that approximately 15.5 million illegal aliens reside within the United States. This number is substantially higher than FAIR’s previous estimate of 14.5 million in 2020.
Based on FAIR’s most recent comprehensive fiscal cost study, illegal aliens are likely imposing a net fiscal burden of at least $143.1 billion. That’s an increase of approximately $9.4 billion over the past year.
This alarming increase in the illegal alien population can be attributed largely to two significant developments:
- The improvement of the United States’ economy as the country re-opens after the peak of the COVID-19 pandemic:
- Businesses are once again hiring, and many unscrupulous employers are using this as an opportunity to turn to reliably cheap labor to undercut the market and make up for lost profits resulting from economic shutdowns stemming from the pandemic. 
- These unethical hiring practices occur even though millions of Americans remain unemployed or underemployed.
- A more significant factor fueling this increase is that the Biden administration has effectively abolished the mission of U.S. Immigration and Customs Enforcement (ICE), preventing the U.S. Customs and Border Protection (CBP) from securing our southern border, and implementing measures that encourage mass illegal immigration. Some of these policy changes include:
- Record apprehensions at both the southern and northern Borders. A total of more than 1.9 million illegal aliens were apprehended at U.S. land borders in FY 2021 – the most on record. Hundreds of thousands of these individuals were released into the country.
- Releasing tens of thousands of ICE-detained illegal aliens. In FY 2021, the administration released more than 143,000 detained illegal aliens into the interior of the country. Additionally, ICE arrested fewer than 60,000 illegal aliens. When more illegal aliens are released into the interior of the country than removed, the illegal alien population is almost certain to grow.
- Reinstating the Obama-era policy of catch-and-release. This dramatically increases the illegal alien population as it allows unlawful migrants to enter the country undetained while they await their court hearings. Many of these individuals fail to appear at their hearings. Those that do appear typically remain in the country for years until their proceedings conclude due to a massive, and growing, backlog of immigration cases.
- Halting Construction of the Border Wall. President Biden made good on his campaign promise to end the construction of a barrier along the Southwest border. Predictably, this has made it easier for illegal aliens and human smugglers to unlawfully enter the U.S. undetected. 
- Gutting the Migrant Protection Protocols (MPP) and Asylum Cooperative Agreements (ACAs). The administration initially cancelled MPP soon after President Biden’s inauguration. Even though a federal judge has since instructed the administration to restart the program, very few migrants have been required to follow the protocols set forth in the rule. The administration has also cancelled the ACAs, which allows for third-country nationals to now asylum shop their way to the U.S. instead of requiring them to apply in the first possible nation.
- Promising amnesty. Since early in his campaign, President Biden has promised to extend amnesty to essentially all illegal aliens in the United States. Since taking office, Congress has tried (and failed) multiple times to pass such an amnesty. Soon after his election, the number of illegal border crossings rose exponentially. Many migrants explicitly claimed that they were entering the United States solely because they felt like President Biden was inviting them.
- Forbidding ICE from arresting immigration lawbreakers. Soon after taking office, President Biden took steps to severely limit ICE officials from detaining and removing most non-criminal immigration lawbreakers. In September of 2021, these limits were expanded to also protect most criminal illegal aliens from deportation.
- Continued abuse of Temporary Protection Status (TPS) programs. The administration has implemented TPS for various new countries, while failing to end any existing designations – even in situations where the original reason for implementation have long been resolved. TPS recipients do not technically hold lawful status in the country, and therefore are included in our estimates. As residents from more and more countries are offered TPS, fewer illegal aliens will be eligible for removal from the country.
Where do Illegal Aliens Live in the United States
Unsurprisingly, most illegal aliens tend to live near the United States’ border with Mexico or in states with sanctuary policies that offer welcoming environments and protection from immigration enforcement. The ten states with the largest estimated illegal alien populations account for just under three-fourths (70.6%) of the national illegal alien total.
However, this does not mean that states which hold a comparatively small share of the illegal alien population are unaffected by its negative effects. In fact, as FAIR has pointed out in other studies, illegal immigration often hits these states the hardest, as it is more difficult for low-population areas to absorb the impacts of illegal immigration.
The following graphics estimate how many illegal aliens reside in each state, as well as the total number of illegal aliens and their children.
2021 Illegal Alien Population Estimate by State
|Total Number of Illegal Aliens by State||Total Number of Illegal Aliens and Their U.S. Born Children|
|*Totals rounded to the nearest thousand.|
Most of the attention regarding the impact of illegal immigration is placed on the Southern border, as well as national figures. However, our research shows that illegal aliens reside throughout the nation, not just near the border. According to a FAIR report, states that are nowhere near the Southern border and have relatively small foreign-born populations have slowly become ideal destinations for illegal aliens.
The various employment opportunities in the manufacturing and agriculture sectors and the lower cost of living in these states are attracting migrants, including illegal aliens. As a result, unlawful migrants have cost Americans fiscally, economically, and socially in these jurisdictions.
For example, despite its relatively small population, FAIR estimates that approximately 6,700 illegal aliens now live in Portland, ME. This has resulted in thousands of lawful and illegal aliens being forced to live in temporary shelters, as well as a drastic increase in crime. So, while that may appear to be a miniscule figure when compared to the illegal alien population in places like Miami, FL, its affects are more acutely felt by local residents.
Listed below is a selection of localities and the number of illegal aliens who are estimated to live there:
|Illegal Alien Population in Select U.S. Cities|
|Location||Total Illegal Aliens||Percentage of Population|
|San Diego County, CA||188,847||5.7%|
|Fairfax County, VA||88,861||7.7%|
|Loudoun County, VA||26,521||6.3%|
|Colorado Springs, CO||12,918||1.7%|
|*All totals are for metro areas as defined by the federal government unless otherwise noted|
Who is an Illegal Alien?
An illegal alien is anyone who:
- Entered the United States without authorization, or
- Anyone who unlawfully remained in the United States once their authorized time of stay expired.
It is important to define exactly who is and is not an illegal alien because many organizations deliberately misclassify some illegal aliens in a dishonest effort to portray that population as smaller than it actually is. Many organizations and mainstream media sources incorrectly classify unaccompanied alien minors (UAMs), recipients of Deferred Action for Childhood Arrivals (DACA), and/or those with Temporary Protected Status (TPS) as being lawfully present in the United States.
Such classifications are inaccurate. Individuals who have been granted any form of deferred action or who have received TPS have not been granted “lawful status.” Rather, federal immigration authorities have acknowledged their unlawful presence and are opting to temporarily defer their removal from the country. These types of limited deportation deferrals are subject to revocation in a wide variety of circumstances.
FAIR offers additional details on who should be considered an illegal alien in our study titled “Why ‘Illegal Alien’ is the Correct Term.”
Difficulty in Estimating the Illegal Alien Population
Estimating the size, distribution, and characteristics of the illegal alien population is an inexact science. The methods used by those claiming to have calculated a definitive figure should be viewed skeptically as there is no completely reliable source of information on illegal aliens. The Department of Homeland Security (DHS) only (loosely) counts foreign nationals who enter and leave the United States in a lawful manner. In truth, we do not know exactly how many people cross the border unlawfully and evade immigration authorities. We can only estimate these figures based on changes in annual census data, along with how many individuals CBP and ICE believe slip through their detection.
Most current estimates regarding the total number of illegal aliens are based on U.S. Census Bureau data. Far too many of these tallies presume that essentially all unlawful migrants are willing to respond to demographic questionnaires and that they provide accurate information to federal officials. As people whose very presence in the United States is an ongoing violation of law, many illegal aliens understandably see no personal value in revealing any information about their nativity. Therefore, when asked about how, when, and why they entered the United States, illegal aliens have a strong motive to either lie, claiming they are lawful migrants or citizens, or refuse to respond at all. There are no repercussions for illegal aliens who fail to respond to annual Census Bureau survey programs such as the American Community Survey (ACS) or the Current Population Survey (CPS).
Indeed, there are few mechanisms in place to verify the accuracy of the information respondents provide. In fact, the Census Bureau’s weighted results from the ACS can vary by millions, depending on what information is requested and how questions are phrased. Because of this, it is important to not solely rely on raw totals from the Census Bureau.
How We Reached our Estimate
To determine FAIR’s estimate of the total number of illegal aliens in the United States, we first calculated an approximate total number of all foreign-born residents currently presumed to be living here. In order to do this, we first analyzed the latest relevant information available from the Census Bureau’s 2020 ACS and 2021 CPS.
Again, it’s important to realize that the ACS and CPS do not capture the entire illegal alien population in the United States. In the past, most reputable research organizations have considered a raw calculation based on these data to be anywhere from 15-35 percent lower than the actual suspected total illegal alien population. This is also in line with the most recent estimates from the federal government. However, most research organizations that produce estimates of the illegal alien population are pro-mass migration, and they dishonestly purport that Census data is almost fully accurate to create a false impression that the illegal alien population in the United States is smaller than it really is.
So, after we subtracted the total number of lawfully present migrants in the country from the total foreign-born population to reach our base illegal alien population, we assume that this total is underestimated by approximately 30 percent. This makes our estimate compatible to the general consensus of non-partisan experts regarding the accuracy of Census data.  Using this method, we reached our estimate of 15.5 million.
 Matt O’Brien and Spencer Raley, “The Fiscal Burden of Illegal Immigration on United States Taxpayers,” Federation for American Immigration Reform, September 2017, https://www.fairus.org/issue/publications-resources/fiscal-burden-illegal-immigration-united-states-taxpayers.
 Bob Dane, “Mayorkas Does Congress’ Work, Issues More Cheap Labor Visas,” ImmigrationReform.com, “March 18, 2022, https://www.immigrationreform.com/2022/03/18/dhs-again-raises-foreign-worker-cap-immigrationreform-com/.
 FAIR Research Team, “2021 Year in Review: Biden’s Immigration Numbers Reveal Record Failures, Costs and to Americans,” Federation for American Immigration Reform, December 2021, https://www.fairus.org/issue/border-security/2021-year-review-biden-immigration-numbers-record-failures-costs.
 FAIR Research Team, “FAIR Uncovers Bombshell ICE Report Revealing Record Low Removals in Fiscal Year 2021,” Federation for American Immigration Reform, February 2022, https://www.fairus.org/issue/illegal-immigration/fair-uncovers-bombshell-ice-report-revealing-record-low-removals-fiscal.
 Todd Bensman, “ ‘Catch and Release’ Resumes on Texas Border in the Face of Rising Migrant Numbers,” Center for Immigration Studies, February 3, 2021, https://cis.org/Bensman/Catch-and-Release-Resumes-Texas-Border-Face-Rising-Migrant-Numbers.
 Adam Shaw, “DHS Chief Reveals Startling Stat on Asylum Seekers Who Skip Hearings, Disappear,” Fox News, June 11, 2019, https://www.foxnews.com/politics/dhs-secretary-reveals-startling-stat-on-asylum-seekers-who-skip-hearings-disappear/
 Muzaffar Chishti and Julia Gelatt, “Mounting Backlogs Undermine U.S. Immigration System and Impede Biden Policy Changes,’” Migration Policy institute, February 2022, https://www.migrationpolicy.org/article/us-immigration-backlogs-mounting-undermine-biden.
 Stephen Dinan, “Joe Biden Border Wall Halt Creates Smugglers’ Highway, Sheriff Says,” The Washington Times, March 3, 2021, https://www.washingtontimes.com/news/2021/mar/3/joe-biden-border-wall-halt-creates-smugglers-highw/.
 Adam Shaw, “Biden Admin Enrolled Fewer Than 300 Migrants in ‘Remain in Mexico’ in December,” Fox News, January 25, 2022, https://www.foxnews.com/politics/biden-admin-enrolled-fewer-migrants-in-remain-in-mexico-in-december.
 Madison McQueen and Jason Pena, “Biden’s Border Crisis 101: How This Administration’s Policies Created a Self-Inflicted Crisis,” Federation for American Immigration Reform, April 2021, https://www.fairus.org/issue/border-security/bidens-border-crisis-101.
 John Kass, “Column: Biden Called for the Border Surge. And Now he Owns It.” Chicago Tribune, March 24, 2021,https://www.chicagotribune.com/columns/john-kass/ct-prem-biden-border-crisis-john-kass-20210324-s6nxh76uofgs3n53xtxcmdpjty-story.html.
 Congressional Research Service, “The Biden Administration’s Immigration Enforcement Priorities: Background and Legal Considerations,” Updated December 10, 2021, https://sgp.fas.org/crs/homesec/LSB10578.pdf.
 Alejandro N. Mayorkas to Tae D. Johnson, September 30, 2021, in Guidelines for the Enforcement of Civil Immigration Law, https://www.ice.gov/doclib/news/guidelines-civilimmigrationlaw.pdf.
 Preston Huennekens, “Mayorkas Grants TPS to Rapidly Resettled Afghans,” Federation for American Immigration Reform, March 2022, https://www.fairus.org/legislation/presidential-administration/amnesty/mayorkas-grants-tps-rapidly-resettled-afghans.
 Matt O’Brien, Spencer Raley, and Casey Ryan, “Small Migrant Populations, Huge Impacts,” Federation for American Immigration Reform, February 2020, https://www.fairus.org/issue/societal-impact/small-migrant-populations-huge-impacts-even-states-few-immigrants-hit-costs.
 Matt O’Brien, Spencer Raley, and Casey Ryan, “Small Migrant Populations, Huge Impacts: Even States with Few Immigrants Hit with Costs, Lost Jobs, “Federation for American Immigration Reform,” January 2020, https://www.fairus.org/press-releases/mass-immigration-has-oversized-negative-impact-low-immigration-states-finds-new-fair.
 FAIR’s estimate of the illegal alien population at the local level is conducted in a similar manner to how we calculate totals at the national and state level. However, since less data is available regarding the distribution of illegal aliens within states, the margin of error for these estimates are higher (approximately +/-8 percent).
 Spencer Raley, “A Small Town Is Paying a Big Price When It Comes to Unplanned, Unvetted Mass Immigration,” ImmigrationReform.com, February 28, 2022, https://www.immigrationreform.com/2022/02/28/mass-migration-small-cities-immigrationreform-com/.
 Matt O’Brien, Spencer Raley, and Casey Ryan, “Why ‘Illegal Alien’ is the Correct Term,” Federation for American Immigration Reform, July 2018, https://www.fairus.org/issue/border-security/why-illegal-alien-correct-term.
 Basing the total number of foreign-born residents in the United States on responses to the ACS question requesting citizenship information typically yields a weighted total that is more than two million individuals lower than when the estimate is based on survey questions regarding how long respondents have lived in the country.
 United States Census Bureau, “American Community Survey,” Accessed December 30, 2020, https://www.census.gov/acs/www/data/data-tables-and-tools/data-profiles/2018/.
 U.S. Department of Homeland Security, “Population Estimates,” December 2018, https://www.dhs.gov/sites/default/files/publications/18_1214_PLCY_pops-est-report.pdf.
 To estimate the total number of lawful migrants in the United States, we examined both data from the ACS, CPS, and the comprehensive “Yearbook of Immigration Statistics” published annually by the DHS. This is the approach most commonly used by other reputable organizations that produce estimates on this matter. Our totals closely resemble the most commonly cited estimate of roughly 35.8 million.
 As noted earlier in this study, most professional statisticians once considered somewhere around 30 percent to be the most accurate assumption for how many illegal aliens are typically missed by the Census. This is also approximately the figure used by the federal government in their most recent projections.
For previous versions of this report, view the PDF versions here: