III. Graph of Unauthorized Resident Alien Population Estimates (in Millions) [Note: Sources may vary by year, and study results may vary within the same year.]
IV. Chart of Unauthorized Resident Alien Population Estimates with Full-Text Reports
"In summary, there were an estimated 11.6 million [Rounded from 11,550,000 by the Department of Homeland Security] unauthorized immigrants living in the United States as of January 2006."
"Based on analysis of other data sources that offer indications of the pace of growth in the foreign-born population, the Center developed an estimate of 11.5 to 12 million for the unauthorized population as of March 2006."
"The number of illegal immigrants in the United States may be as high as 20 million people, more than double the official 9 million people estimated by the Census Bureau."
*[Editor's Note:Because the Bear Stearns estimate is so much higher than the other unauthorized resident alien population estimates we referenced on this page, we have provided a critique of the study for additional perspective.
Jeffrey Passel, PhD, Senior Demographer at the Pew Hispanic Center, wrote the following statements about the Bear Stearns study in a Sep. 1, 2009 email to ProCon.org:
"[Y]our inclusion of the Bear-Stearns 'estimate' with the others is very misleading. At no point in the Bear-Stearns report do the authors describe a methodology for deriving their estimate. The figure they report is purely speculative and not supported by any underlying data. In fact, several of the 'indicators' that they point to as supporting higher figures than others are, in fact, consistent with the other, lower estimates and inconsistent the higher Bear-Stearns ‘estimate.’ I discuss this paper in more detail in a paper published by the OECD [Organisation for Economic Co-Operation and Development] (especially at paragraphs 61-65)."]
"Our best estimate, based on the March 2002 Current Population Survey and other data sources, is that there are 9.3 million undocumented immigrants in the country. They represent 26 percent of the total foreign-born population."
"In the case of the total unauthorized population, we estimate that the size of this group in mid-2001 varies from a low of about 5.9 million to a high of about 9.9 million, with a mid-range estimate of about 7.8 million. In the case of the Mexican unauthorized population, we estimate that the size of this group varies from a low of about 3.4 million to a high of about 5.8 million, with a mid-range estimate of about 4.5 million. In the case of the non-Mexican Central American unauthorized population, we estimate that the size of this group varies from a low of about 1.2 million to a high of about 1.9 million, with a mid-range estimate of about 1.5 million."
"DHS [Department of Homeland Security] estimates that the unauthorized immigrant population in the United States increased 24 percent from 8.5 million on January 1, 2000 to 10.5 million on January 1, 2005."
"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."
"In its last set of estimates, INS [Immigration and Naturalization Service] estimated that the population was 5.0 million in October 1996... In 1994, the INS developed the first detailed national estimates of the unauthorized immigrant population residing in the United States. Those estimates indicated that the unauthorized resident population was 3.4 million as of October 1992..."
"...the 'April 1983 [U.S. Census Bureau] Current Population Survey' included over two million (2,093,000) undocumented aliens aged fourteen years and over... Just over 30 percent of the two million entered the United States during 1980-1983 and nearly one-half came to the country during the 1970s."
"...estimates of the number counted in the census [1980] provide a firm empirical basis for setting a lower bound on the total in the country as of 1980. The estimates presented in this paper, along with the results of other studies (Panel on Immigration Statistics, 1985), suggest that the undocumented Mexican population in 1980 was in the 1-2 million range, with the total number from all countries falling in the range of 2-4 million. [...] Of the undocumented present and counted in 1980, 941,000 entered during 1975-1980; 576,000 entered during 1970-1974; and 540,000 entered before 1970 [and after passage of the Immigration Act of 1965]. [...] Finally, the estimates for 1980 show a high proportion of recent arrivals, and very few who entered the United States prior to 1960."
** Average between 2 and 4 million *** Sum of 540,000 (1969) and 576,000 (1970 - 1974) **** "before 1970" and after 1965 was interpreted by ProCon.org to mean as of 1969
[Editor's Note: On March 27, 2007, we called the U.S. Census Bureau to get pre-1970 statistics, and were told that the "Census survey does not ask for legal status information," and that the existing estimates are based on "residual studies" which were not available until the 1970s. We also called the Department of Homeland Security Office of Immigration Statistics and were told that "data prior to 1970 are scarce," and "early estimates are not reliable." We did find a statement from the U.S. General Accounting Office explaining why pre-1970 information is so hard to find:
"The illegal alien population is constantly in flux. Individuals enter and exit this population daily by making covert border crossings, by taking unauthorized employment, by failing to leave when their visas expire, by dying, and as a result of INS [Immigration and Naturalizations Service] decisions. Policymakers need to know the size of the population at particular moments and the volume of immigration over periods of time. Although illegal immigration has been a concern since the introduction of immigration curbs in 1875, deliberate attempts to estimate the population size reliably were not made until the 1970's."
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