Order Code RL33874
Unauthorized Aliens Residing in the
United States: Estimates Since 1986
February 28, 2007
Ruth Ellen Wasem
Specialist in Immigration Policy
Domestic Social Policy Division
Unauthorized Aliens Residing in the United States:
Estimates Since 1986
Summary
Estimates derived from the March Supplement of the U.S. Census Bureau’s
Current Population Survey indicate that the unauthorized resident alien population
(commonly referred to as illegal aliens) has risen from 3.2 million in 1986 to 11.1
million in 2005. The estimated number of unauthorized aliens had dropped to 1.9
million in 1988 following passage of a 1986 law that legalized several million
unauthorized aliens. About two-thirds of the unauthorized population in 2005 were
estimated to have entered the United States in the past decade.
Similarly, the Department of Homeland Security’s Office of Immigration
Statistics (OIS) reported an estimated 10.5 million unauthorized alien residents as of
January 2005, up from 8.5 million in January 2000. The OIS estimated that the
unauthorized immigrant population in the United States increased by 24%, with an
annual average increase of 408,000 unauthorized aliens over the past five years.
Research suggests that various factors have contributed to the increase in
unauthorized resident aliens in recent years, and that the rise is often attributed to the
“push-pull” of prosperity-fueled job opportunities in the United States in contrast to
limited or nonexistent job opportunities in the sending countries. Some observers
maintain that lax enforcement of employer sanctions for hiring unauthorized aliens
has facilitated this “push-pull,” but it is difficult to demonstrate this element
empirically.
Some researchers are now suggesting that the increased unauthorized resident
population is an inadvertent consequence of border enforcement and immigration
control policies. They posit that strengthened border security has curbed the fluid
movement of seasonal workers. They also cite the backlog in processing immigrant
petitions, which some argue lead aliens to risk residing without legal status with their
family in the United States while they wait for the petitions to be processed or visas
to become available.
Some observers point to more elusive factors when assessing the increase of
unauthorized resident aliens — such as shifts in immigration enforcement priorities
away from illegal entry to removing suspected terrorists and criminal aliens, or
discussions of possible “amnesty” legislation. Others argue that border security
measures enacted in recent years have not received adequate funding to be effective
against unauthorized migration.
This report does not track legislation and will be updated as needed.
Contents
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Estimates Since 1986 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Unauthorized Alien Residents in 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Office of Immigration Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Contributing Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
List of Figures
Figure 1. Estimated Number of Unauthorized Resident Aliens, 1986-2005 . . . . 3
Figure 2. Unauthorized Resident Alien Population by Place of Origin,
1986 and 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3. Unauthorized Resident Aliens in 2005, by Reported Year of
Arrival . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Unauthorized Aliens Residing in the
United States: Estimates Since 1986
Background
An estimated 37 million foreign-born people reside in the United States. In
recent years, the United States typically admitted or adjusted 600,000 to 1 million
aliens annually, giving them the status of “legal permanent resident” (LPR), a term
synonymous with the term immigrant. In addition to those foreign nationals who
permanently reside legally in the United States, millions each year come temporarily
on nonimmigrant visas, and some of these nonimmigrants (e.g., foreign students and
intra-company business transfers) may reside legally in the United States for several
years. It is also estimated that each year hundreds of thousands of foreign nationals
overstay their nonimmigrant visas.1
The three main components of the unauthorized resident alien population are (1)
aliens who overstay their nonimmigrant visas, (2) aliens who enter the country
surreptitiously without inspection, and (3) aliens who are admitted on the basis of
fraudulent documents. In all three instances, the aliens are in violation of the
Immigration and Nationality Act (INA) and subject to removal.
The last major law that allowed unauthorized aliens living in the United States
to legalize their status was the Immigration Reform and Control Act (IRCA) of 1986
(P.L. 99-603). Generally, legislation such as IRCA is referred to as an “amnesty” or
a legalization program because it provides LPR status to aliens who are otherwise
residing illegally in the United States. Among IRCA’s main provisions was a time-
limited legalization program, codified at § 245A of the Immigration and Nationality
Act, that enabled certain illegal aliens who entered the United States before January
1, 1982, to become LPRs.2 It also had a provision that permitted aliens working
illegally as “special agricultural workers” to become LPRs.3 Nearly 2.7 million
aliens established legal status through the provisions of IRCA.
Continued high levels of unauthorized migration to the United States have, in
part, prompted the current discussion of guest worker programs, as well as major
proposals that would permit legalization under specified conditions. There are also
proposals aimed at reducing unauthorized migration by tightening up enforcement
1 See CRS Report RS22446, Nonimmigrant Overstays: Brief Synthesis of the Issue, by Ruth
Ellen Wasem.
2 8 U.S.C. § 1255a.
3 8 U.S.C. § 1160.
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of immigration laws.4 The report of the National Commission on Terrorist Attacks
Upon the United States (also known as the 9/11 Commission) stated that “more than
9 million people are in the United States outside the legal immigration system” as
one of the reasons for the Commission’s recommendations to improve immigration
services and strengthen enforcement of immigration laws.5
This CRS report presents data estimating the number of unauthorized aliens who
have been living in the United States since 1986. There have been a variety of
estimates of the unauthorized resident alien population over this period, sometimes
with substantially different results. This report is limited to data analyses of the
Current Population Survey (CPS) conducted by the U.S. Census Bureau and the
Bureau of Labor Statistics so that there is a basic standard of comparison over time.6
Estimates Since 1986
For a basis of comparison, Figure 1 presents the estimate of 3.2 million
unauthorized resident aliens in 1986 calculated by demographers Karen Woodrow
and Jeffrey Passel, who worked for the U.S. Census Bureau at that time. As expected
after the passage of IRCA, the estimate for 1988 dropped to 1.9 million.7 According
to demographer Robert Warren of the former Immigration and Naturalization Service
(INS), the estimated unauthorized resident alien population grew to 3.4 million in
1992 and to 5.0 million in 1996.8 By the close of the decade, the estimated number
4 For a discussion of proposals in the previous Congress, see CRS Report RL33125,
Immigration Legislation and Issues in the 109th Congress, coordinated by Andorra Bruno.
5 For a discussion of these recommendations, see National Commission on Terrorist Attacks
Upon the United States, The 9/11 Commission Report, chap. 12.4, pp. 383-391, July 2004.
6 The demographers who conducted these analyses used some variant of a residual
methodology to estimate the population (i.e., the estimated population remaining after
citizens and authorized aliens are accounted for), another reason they were selected for this
comparison. Demographers at the U.S. Census Bureau also have used a similar
methodology to estimate the residual foreign born population in the 2000 decennial census,
and they reported the following: “According to our calculations, the estimated residual
foreign-born population counted in the 2000 census was 8,705,419. Assuming a 15-percent
undercount rate yields a population of 10,241,669 in 2000.” They point out that the
category of residual foreign born includes “quasi legal aliens” (i.e., aliens without legal
status who have petitions pending or court cases underway that potentially would give them
LPR status), as well as unauthorized aliens, and thus should not be considered an official
estimate of unauthorized resident aliens. U.S. Census Bureau, Population Division Working
Paper 61, Evaluating Components of International Migration: The Residual Foreign Born,
by Joseph M. Costanzo, Cynthia Davis, Caribert Irazi, Daniel Goodkind, and Roberto
Ramirez (June 2002).
7 Karen Woodrow and Jeffrey Passel, “Post-IRCA Undocumented Immigration to the United
States: An Analysis Based on the June 1988 CPS,” in Undocumented Migration to the
United States, by Frank D. Bean, Barry Edmonston, and Jeffrey Passel (RAND Corporation,
1990).
8 Annual Estimates of the Unauthorized Immigrant Population Residing in the United States
(continued...)
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of unauthorized alien residents had more than doubled. Passel, now at the Pew
Hispanic Center, estimated the unauthorized population in 2000 at 8.5 million, but
this latter estimate included aliens who had petitions pending or relief from
deportation.9
Figure 1. Estimated Number of Unauthorized Resident Aliens,
1986-2005
12
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9.3
8.5
8
1.5
illions
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6
5.8
in
0.8
10.5
r (
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b
4
3.2
3.5
3.4
7.0
m
1.9
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0
1986
1988
1990
1992
1996
2000
2002
2004
2005
Woodrow and Passel
Warren
Revised Warren
Passel, Capps, and Fix
Hoefer, Rytina, and Campbell
Passel
Sources: CRS presentation of analysis of Current Population Survey data conducted by Karen
Woodrow and Jeffrey Passel (1986 and 1990); Robert Warren (1996, 2000, and 2003); Jeffrey Passel,
Randy Capps, and Michael Fix (2002); Passel (2000, 2005, and 2006); and Michael Hoefer, Nancy
Rytina, and Christopher Campbell (2006).
Subsequently, Warren estimated that there were 7.0 million unauthorized aliens
residing in the United States in 2000. As depicted in Figure 1, he also revised his
earlier analyses using the latest CPS and estimated that there were 3.5 million
unauthorized aliens living in the United States in 1990 and 5.8 million in 1996.
Warren excluded “quasi-legal” aliens (e.g., those who had petitions pending or relief
from deportation) from his estimates.10 By 2002, the estimated number of
8 (...continued)
and Components of Change: 1987 to 1997, by Robert Warren, Office of Policy and
Planning, U.S. Immigration and Naturalization Service, Sept. 2000.
9 U.S. Congress, House Committee on the Judiciary, Subcommittee on Immigration and
Claims, Hearing on the U.S. Population and Immigration, Aug. 2, 2001.
10 U.S. Immigration and Naturalization Service, Estimates of the Unauthorized Immigrant
Population Residing in the United States, 1990 to 2000, Jan. 31, 2003.
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unauthorized resident aliens had risen to 9.3 million.11 During the first decade after
IRCA, researchers projected that the net growth in unauthorized aliens had averaged
about 500,000 annually; more recent analyses estimated the average growth at
700,000 to 800,000 annually. If the later trend held, about 12 million unauthorized
aliens may have been residing in the United States by the close of 2006.12
Unauthorized Alien Residents in 2005
The most commonly-cited published estimate based upon the March 2006 CPS
is that 11.1 million unauthorized aliens were residing in the United States.
According to this analysis by Passel, Mexicans made up more than half of
undocumented immigrants — 56 % of the total, or about 6.2 million. He estimated
that 2.5 million (22%) were from other Latin American countries. About 13% were
from Asia, 6% from Europe and Canada, and 3% from the rest of the world.13
As Figure 2 illustrates, the 2005 distribution by region of origin was similar to
Woodrow and Passel’s analysis of the 1986 data, despite the growth in overall
numbers from 3.2 million in 1986 to 11.1 million in 2005. In 1986, 69% of the
unauthorized aliens residing in the United States were estimated to be from Mexico,
compared with 56% in 2005. Asia’s share of the unauthorized alien residents
appeared to have grown over this period (from 6% to 13%), as did the portion from
the “other” parts of the world. Note that Canada is grouped with North and South
America (excluding Mexico) in 1986 and with Europe in 2005.14
Passel estimated the number of persons living in families in which the head of
the household or the spouse is an unauthorized alien was 14.6 million as of March
2005. Passel also reported that in 2005 there were an estimated 1.8 million children
who were unauthorized and an estimated 3.1 million children who were U.S. citizens
by birth living in families in which the head of the family or a spouse was
unauthorized. He projected that unauthorized aliens accounted for about 4.9% of the
civilian labor force in March 2005, or about 7.2 million workers out of a labor force
of 148 million.15
11 The Urban Institute, Undocumented Immigrants: Facts and Figures, by Jeffrey Passel,
Randy Capps, and Michael Fix, Jan. 12, 2004.
12 Pew Hispanic Center, Estimates of the Size and Characteristics of the Undocumented
Population, by Jeffrey Passel, Mar. 21, 2005.
13 Pew Hispanic Center, Size and Characteristics of the Unauthorized Migrant Population
in the U.S.: Estimates Based on the March 2005 Current Population Survey, by Jeffrey
Passel, Mar. 7, 2006.
14 Ibid.
15 For a discussion of how many unauthorized aliens are currently in the U.S. workforce, see
CRS Report RL32044, Immigration: Policy Considerations Related to Guest Worker
Programs, by Andorra Bruno.
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Figure 2. Unauthorized Resident Alien Population by Place of Origin,
1986 and 2005
1986
2005
Mexico
56%
Mexico
69%
Other
3%
Asia
6%
Europe
Asia
2%
13%
North & South America
23%
Europe &
Canada
Other Latin America
6%
22%
3.2 million
11.1 million
Source: CRS presentation of analysis of Current Population Survey data conducted by Karen Woodrow and
Jeffrey Passel (1990), and Jeffrey Passel (2006).
According to Passel, the largest share of the unauthorized population (4.4
million aliens) had been in the country five years or less. As Figure 3 depicts, about
two-thirds of the unauthorized population were estimated to have entered the United
States during the decade 1995-2005.16
16 Pew Hispanic Center, Size and Characteristics of the Unauthorized Migrant Population
in the U.S.: Estimates Based on the March 2005 Current Population Survey, by Jeffrey
Passel, Mar. 7, 2006.
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Figure 3. Unauthorized Resident
Aliens in 2005, by Reported Year of
Arrival
Pre-1990
16.2%
1.8 million
2000-2005
39.6%
4.4 million
1990-1994
2.0 million
18.0%
2.9 million
1995-1999
26.1%
Source: CRS presentation by analysis of Current Population Survey data conducted by Jeffrey Passel
(2006).
Office of Immigration Statistics
The Department of Homeland Security’s (DHS’s) Office of Immigration
Statistics (OIS) recently published its estimates of the unauthorized resident alien
population and yielded results consistent with Passel’s discussed above. The OIS
reported an estimated 10.5 million unauthorized alien residents as of January 2005,
up from 8.5 million in January 2000. The DHS estimated that the unauthorized
immigrant population in the United States increased by 24%, with an annual average
increase of 408,000 unauthorized aliens over the past five years.17
According to the OIS, California had more unauthorized residents than any other
state — an estimated 2.8 million unauthorized aliens in 2005. Texas followed with
nearly 1.4 million, and Florida had 850,000. Among the 10 leading states of
residence of the unauthorized population in 2005, OIS reported that those with the
largest average annual increases since 2000 were Texas (54,000), California (52,000),
and Georgia (50,000). The states with the greatest percentage increases in
unauthorized immigrants from 2000 to 2005 were Georgia (114%), Arizona (45%),
Nevada (41%), and North Carolina (38%).18
17 Department of Homeland Security, Office of Immigration Statistics, Estimates of the
Unauthorized Immigrant Population Residing in the United States: January 2005, by
Michael Hoefer, Nancy Rytina, and Christopher Campbell, 2006.
18 Op. cit. For alternative analyses, see Pew Hispanic Center, Estimates of the Unauthorized
Migrant Population for States based on the March 2005 CPS, by Jeffrey Passel, Apr. 26,
2006.
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Contributing Factors
The research points to various factors that have contributed to the increase in
unauthorized resident aliens. Historically, unauthorized migration is generally
attributed to the “push-pull” of prosperity-fueled job opportunities in the United
States in contrast to limited or nonexistent job opportunities in the sending
countries.19 Some observers maintain that lax enforcement of employer sanctions for
hiring unauthorized aliens has facilitated this “push-pull,” but it is difficult to
demonstrate this element empirically. Political instability or civil unrest at home is
another element that traditionally has induced people to risk unauthorized migration,
but the motives for such migrations are sometimes mixed with the economic
hardships often correlated with political upheaval.20
Although most policy makers have assumed that tighter border enforcement
would reduce unauthorized migration, some researchers are now suggesting that the
strengthening of the immigration enforcement provisions, most notably by the
enactment of the Illegal Immigration Reform and Immigrant Responsibility Act of
1996 (IIRIRA), may have inadvertently increased the population of unauthorized
resident aliens.21 This perspective argues that IIRIRA’s increased penalties for illegal
entry, coupled with increased resources for border enforcement, stymied what had
been a rather fluid movement of migratory workers along the southern border; this
in turn raised the stakes in crossing the border illegally and created an incentive for
those who succeed in entering the United States to stay.22
Another contributing factor — best represented by the “quasi-legal” aliens
discussed above — is the wait-times for immigrant petitions to be processed and
visas to become available to legally come to the United States. There are statutory
ceilings that limit the number of immigrant visas issued each year. There are also
significant backlogs in processing petitions because of the high volume of aliens
eligible to immigrate to the United States and the large number eligible to become
U.S. citizens. Of the pending cases, reportedly almost 2 million are immediate
19 For further analysis, see CRS Report RL32982, Immigration Issues in Trade Agreements,
by Ruth Ellen Wasem.
20 For a summary of this research, see Commission for the Study of International Migration
and Cooperative Economic Development, Unauthorized Migration: An Economic
Development Response, Appendix E, July 1990.
21 For trends in apprehensions of unauthorized aliens, see CRS Report RL32562, Border
Security: The Role of the U.S. Border Patrol, by Blas Nuñez-Neto.
22 For analysis of the IIRIRA’s effect on unauthorized alien residents, see Wayne Cornelius,
“Death at the Border: Efficacy and Unintended Consequences of U.S. Immigration Control
Policy,” Population and Development Review, vol. 27, no.4 (December 2001). For an
analysis of the reduction in unauthorized alien apprehensions after IRCA, see Thomas J.
Espenshade, “Undocumented Migration to the United States: Evidence from a Repeated
Trials Model,” in Undocumented Migration to the United States, by Frank D. Bean, Barry
Edmonston, and Jeffrey Passel (RAND Corporation, 1990).
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relative and family preference petitions.23 Many observe that these family members
sometimes risk residing without legal status with their family in the United States
while they wait for the petitions to be processed or visas to become available.
Some observers point to more elusive factors — such as shifts in immigration
enforcement priorities away from illegal entry to removing suspected terrorists and
criminal aliens, or discussions of possible “amnesty” legislation — when they assess
the increase of unauthorized resident aliens. Others argue that border security
measures enacted in recent years have not received adequate funding to be effective
against unauthorized migration, and some maintain that state and local law
enforcement officers have not been sufficiently involved in apprehending illegal
aliens. Some would make illegal presence an aggravated felony.24 Still others assert
that there has not been sufficient funding and staffing for enforcement of immigration
laws in the interior of the country.25 It is difficult to measure whether, or to what
extent, these other phenomena have contributed to the increase in unauthorized
resident aliens.
crsphpgw
23 For analysis of immigration admissions, visa priority dates, and backlogs, see CRS Report
RL32235, U.S. Immigration Policy on Permanent Admissions, by Ruth Ellen Wasem.
24 For a full discussion of these legal and policy issues, as well as legislative options, see
CRS Report RL33125, Immigration Legislation and Issues in the 109th Congress,
coordinated by Andorra Bruno, and CRS Report RL33181, Immigration Related Border
Security Legislation in the 109th Congress, by Blas Nuñez-Neto.
25 For a summary of recent funding, see CRS Report RL33049, FY2006 Appropriations for
Border and Transportation Security, and CRS Report RL33428, Homeland Security
Department: FY2007 Appropriations, both coordinated by Jennifer E. Lake and Blas
Nuñez-Neto.