How many illegal aliens reside in the United States?

by Fred Elbel

This section presents an introduction to alternative methodologies to accurately estimate the number of illegal alien invaders living in the United States. To read the detailed analysis, please see:

How many illegal aliens reside in the United States? A methodology using Border Patrol "got away" statistics, by Fred Elbel.

The mainstream media, whenever it actually mentions the number of illegal aliens living in the United States, categorically quotes the official government figure of 8-12 million. This number originated with the Department of Homeland Security, which in December 2003 estimated 8 million to 12 million illegal aliens resided in the United States and that 700,000 new illegals enter each year and remain in the country.1 Those stale, outdated estimates have not changed for over 13 years, even though the official annual increase alone would yield a corrected estimate of 15.7 million to 19.7 million illegal aliens today (not adjusting for Obama's unconstitutional 2014 executive amnesty). 

Even though it is quite clear that huge numbers of illegal aliens sneak into our country and avoid capture at our border, the media as well as government agencies seem quite content to under-report these numbers. The static official estimates are somewhat suspect, as they are produced by the very entity responsible for the tidal wave of illegal aliens entering our nation - the United States Government. Alternative methodologies estimate a range of numbers that is likely more realistic. 

Nancy Boulton observes that:

Estimates of the size of the illegal alien population currently living in the U.S. range from about 12 million to over 20 million. The lower number is based on Census Bureau estimates of the foreign-born population in various Census Bureau surveys. The larger number is based on methodology that is not reliant on a respondent’s candor... it is virtually impossible to get an accurate count of populations who are resistant to being identified. Given the problem of porous borders and incentives to avoid detection, the higher estimate is not unreasonable.5

Indeed, U.S. Border Patrol Local 2544 stated in July of 2005:

“There are currently 15 to 20 million illegal aliens in this country by many estimates, but the real numbers could be much higher and the numbers increase every day because our borders are not secure (no matter what the politicians tell you—don’t believe them for a second).

Alternative methodologies

Alternative methodologies conclude that between 20 million and 40 million illegal aliens have evaded apprehension and live in the United States. 

The official number was questioned by D.A. King of The Dustin Inman Society in 2004. Subsequently, an in-depth analysis was published by Fred Elbel1,7. In 2007, The Social Contract published an entire issue addressing the numbers of illegal aliens in the US2.

Nancy Boulton pointed out that two researchers at Bear Stearns Asset Management estimated that the number of illegal immigrants in 2005 could be as high as 20 million. Their figures were based on an analysis of the large discrepancy between official census estimates and growth in indicators such as remittances to the countries of origin, school enrollment and building permits.5,8

Bolton also notes that:

If even one person is successful for every apprehension, it implies over 1 million foreigners per year illegally cross our southern border. In addition, there are roughly 30 million foreign nationals admitted to the U.S. each year on temporary visas. There are no data on the percentage of these visitors who overstay their visas, but data from the Australian Department of Immigration and Multicultural Affairs indicate about 8 percent of those admitted to that country on temporary visas overstay their visa and about 86 percent of those overstay by a year or more. If just 1 percent of the 30 million admitted on temporary visas to the U.S. do not leave as they are required to, that adds another 300,000 foreigners illegally in the U.S. each year.

The analysis by James H. Walsh notes that estimates compiled by the U.S. Census Bureau (USCB), national surveys, governmental agencies, philanthropic organizations, religious charities, nongovernment statistics-keeping agencies, and immigrant advocates range from 7 million to 20 million illegal aliens. Walsh concludes that the number is closer to 2 times 20 million, or 40 million.4 Walsh notes that in 1992, investigation by the U.S. Department of Justice Inspector General found INS statistics suspect and cited deliberate deception by senior INS officials tampering with immigration statistics... U.S. Border Patrol agents confided that they were told to cap apprehensions and deportations to conform to the desires of various Administrations to create at least a public perception of border control.

Walsh also notes that:

In addition, the U.S. Census Bureau routinely undercounts and then adjusts upward total census numbers of Hispanics and other foreign nationals residing in the United States––counting only, of course, those willing to be counted. For the year 2000, the Census Bureau reported a total U.S. population count of “about 275 million” men, women, and children. When the states and local governments challenged that number as an undercount, the total was corrected upward to 281.4 million, with no clear count of illegal aliens. The Hispanic 2000 census count was 32.8 million, but on re-count the Census Bureau adjusted this number upward to 35.3 million, a 13 percent increase.

Walsh focuses on the ratio of illegal alien apprehensions to those who escaped apprehension, noting that:

The average number of recorded apprehensions of illegal aliens in the United States now hovers at 1.2 million a year [in 2007]. A DHS report, Border Apprehensions: 2005, documented 1.3 million apprehensions in 2005. For the 10-year period (1996–2005), the highest number of apprehensions, 1.8 million, occurred in 2000, and the lowest, 1 million, in 2003. These DHS statistics contradict persistent statements by other government agencies that only 400,000 to 500,000 illegal aliens enter the country each year.
Journeymen Border Patrol agents (on the job five years or more) estimate that a minimum of five illegal aliens enter the United States for each apprehension, and more likely seven. That informed estimate would raise the total number of illegal aliens entering the United States in 2003 to 8 million men, women, and children.

He concludes that:

My estimate of 38 million illegal aliens residing in the United States is calculated, however, using a conservative annual rate of entry (allowing for deaths and returns to their homelands) of three illegal aliens entering the United States for each one apprehended. My estimate includes apprehensions at the Southern Border (by far, the majority), at the Northern Border, along the Pacific, Atlantic, and Gulf of Mexico coasts, and at seaports and airports. Taking the DHS average of 1.2 million apprehensions per year and multiplying it by 3 comes to 3.6 million illegal entries per year; then multiplying that number by 10 for the 1996–2005 period, my calculations come to 36 million illegal entries into the United States. Add to this the approximately 2 million visa overstays during the same period, and the total is 38 million illegal aliens currently in the United States.

Elbel also focused on the ratio of border apprehensions to "get-aways". The methodology used in his analysis was as follows:7

  1. Estimate the gross number of illegals entering the U.S., as well as the number of those that evade apprehension by the Border Patrol. A “get away” ratio is applied to the numbers of illegals entering, resulting in a gross estimate of illegals entering and evading apprehension.
  2. Factor in repeat apprehensions of the same individuals and legalizations out of the overall estimate. Many illegal aliens who are apprehended and are returned home try to enter the U.S. again and are subsequently apprehended. Others are legalized and are allowed to stay in the U.S.
  3. Factor “short term stays” from the overall estimate. Some illegal aliens voluntarily return home in less than year.
  4. Estimate the total number of illegal aliens living in the United States, based upon the estimate of illegals entering and evading apprehension each year.

Elbel's conclusion was that it is likely that at least 20 million illegal aliens presently reside in the United States, with up to 12,000 additional illegal aliens entering every day.

In the January, 2013 article, "Over the line: Fighting corruption on our border", Arizona rancher John Ladd stated "I say about a half a million people have been caught on the ranch. And that's what's been caught - that's not what's got through." 

The promise of amnesty

One of the driving factors that results in unending illegal immigration into the United States is simply the mention of a possible amnesty. Holding out the carrot of amnesty has been sufficient to keep wave of wave of illegal aliens sneaking into the United States. The result is that corporations get thousands upon thousands of new consumers, Republicans get an unending stream of cheap foreign labor, and Democrats get wave after wave of "undocumented Democrats".


Using the latest conservative Census Bureau data from 2010 and 2011, the Center for Immigration Studies reports that more than 50 million immigrants (legal and illegal) live in the United States, and that "Absent a change in policy, between 12 and 15 million new immigrants (legal and illegal) will likely settle in the United States in the next decade. And perhaps 30 million new immigrants will arrive in the next 20 years."10

The magnitude of the numbers of illegal aliens in the United States represents a serious crisis and urgent need for a return to the rule of law and secured borders that the United States Constitution demands.



1. "How many illegal aliens reside in the United States? A methodology using Border Patrol 'got away' statistics," by Fred Elbel. Also published as "Illegal immigration invasion numbers analysis", Fred Elbel,, August, 2004, and in the 2007 Social Contract.7

2. “How many illegal aliens are in the U.S.?” The Social Contract (Summer 2007).  The issue includes the following articles:

3. "Introduction: How Many Foreign Nationals Actually Live in the U.S. Illegally?", Diana Hull, Ph.D., Summer 2007

4. "Illegal Aliens: Counting the Uncountable",  James H. Walsh, Summer 2007

5. "The Challenge of Accurately Estimating the Population of Illegal Immigrants", Nancy Bolton, Summer 2007

6. "Racing Backwards - The Fiscal Impact of Illegal Immigration in California, Revisited", Philip J. Romero, Summer 2007

For additional references, see citations and endnotes in the above articles.

7. "How Many Illegal Aliens Are in the U.S.? - An Alternative Methodology for Discovering the Numbers", Fred Elbel, Summer 2007

8. "The Underground Labor Force is Rising to the Surface." Robert Justich and Betty Ng, Bear Stearns Asset Management, Inc. January 2005. Partial excerpt. Also archived on the Wayback Machine. Excerpts:

“Though we cannot conduct an independent census of the United States population, as investors, we need not accept the accuracy of the official census immigration statistics, which are widely recognized as incomplete. There are many ancillary sources of data that provide evidence that the rate of growth in the immigrant population is much greater than the Census Bureau statistics. School enrollments, foreign remittances, border crossings, and housing permits are some of the statistics that point to a far greater rate of change in the immigrant population than the census numbers. At the risk of appearing dogmatic or taking a leap of faith, we have applied the rate of growth from these other areas and have drawn several conclusions about the current immigration population:

1. The number of illegal immigrants in the United States may be as high as 20 million people, almost double the official estimates of 11.1 million of the March 2005 Current Population Survey and 11.5 million–12 million by the Pew Hispanic Center (Fact Sheet, April 5, 2006).

2. The total number of legalized immigrants entering The United States since 1990 has averaged 962,000 per year. Several credible studies indicate that the number of illegal entries has recently crept up to 3 million per year, triple the authorized figure.

3. Undocumented immigrants are gaining a larger share of the job market, and hold approximately 12 to 15 million jobs in the United States (8 percent of the employed)…”

9. U.S. Border Patrol Local 2544 (covering most of Arizona) stated on their website at in July of 2005:

There are currently 15 to 20 million illegal aliens in this country by many estimates, but the real numbers could be much higher and the numbers increase every day because our borders are not secure (no matter what the politicians tell you—don’t believe them for a second).”

10."Immigrants in the United States, 2010: A Profile of America's Foreign-Born Population", Steven A. Camarota, Center for Immigration Studies, August 2012

11. Update: "Border security faults may be result of poor analysis - Homeland Security ignores data it collects on illegal crossings, critics say", AZCentral, July 20, 2013:

'Last year, for example, a panel of leading statisticians, economists and demographers at the National Academy of Sciences conducted a study on illegal immigration at the request of Homeland Security...

That study, which included data from Mexican governmental sources and previous U.S. academic studies, suggested that about three-quarters of those who decide to cross keep trying until they make it. Other outside studies have found 85 or even 90 percent make it...

“Almost everybody who really tries eventually gets in,” said Jeffrey Passel, a member of the panel and a senior demographer at the Pew Hispanic Center, a nonpartisan research organization in Washington, D.C., that studies the U.S. Hispanic population...
[in 2006-2007] CBP asked the Homeland Security Institute, a federally funded research center, to study border-crossing recidivism and the likelihood of apprehending crossers. The study found that, from 2001 to 2005, when border security and the consequences imposed on crossers were both relatively slight, the likelihood of being apprehended on any crossing attempt was about 35 percent, according to sources familiar with the study. But to this day, that study, completed in 2007, remains classified...'

12. White House lies about terrorist threat at border, Tom Tancredo, World Net Daily, September 12, 2014.

13. You Only Think You Know How Many Illegal Immigrants Live in the US, William Campenni, The Daily Signal, December 27, 2015.

...Though now dated, these numbers implied many more illegal immigrants in 2005 than were acknowledged by Pew and the Center for Immigration Studies.

Why, then, has the 11 million figure become so sacrosanct?

Well, professional and institutional reputations are invested heavily in the number, perhaps because with its longevity the public has become comfortable or apathetic. Were it 20 million or more–a larger population than New York state–Americans might be getting really angry.

Imagine the reaction if the media reported daily that this 20 million cohort, supplemented by chain migration and family reunification mandates, would swell to 40 million or 50 million in a decade...

The Heritage Foundation has suggested that if given amnesty, 11 million illegal immigrants would cost taxpayers $6 trillion or more over the immigrants’ lifetimes.

While not exactly linear, those costs would double or more should the real count be in the range of 20 million to 30 million. That money could buy a lot of high schools, highways and health care for Americans...

Let’s question that 11 million. It’s not Scripture. It’s a guess.

14. Damning report on illegal alien entries - nearly 50% sneak into America undetected, Center for Immigration Studies, December 2, 2016.

15. Ivy League Study: Illegal Population is 22 Million, Double Establishment Estimate, Breitbart, September 21, 2018.

The actual study: The number of undocumented immigrants [illegal aliens] in the United States: Estimates based on demographic modeling with data from 1990 to 2016, by Mohammad M. Fazel-Zarandi, Jonathan S. Feinstein, Edward H. Kaplan, PLOS, September 21, 2018

Yale Study Finds Twice as Many Undocumented Immigrants [illegal aliens] as Previous Estimates, by Mohammad M. Fazel-Zarandi, Jonathan S. Feinstein, Edward H. Kaplan, PLOS, September 21, 2018, Yale Insights, September 21, 2018. Includes video discussion by the authors.

However, it should be noted that the Center for Immigration Studies claims the New Estimate of 22 Million Illegal Immigrants Is Not Plausible, by Steven A. Camarota, September 22, 2018 .