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Estimates of the illegal immigrant population in the United States vary widely. Following are four frequently cited numbers and how they were obtained.


-- Swati Pandey

Estimate: 11 million as of March 2005

(33%) (Illegal immigrants as a percentage of all immigrants (U.S. census estimate: 34 million).

Source: Pew Hispanic Center, a private nonpartisan research group that studies the U.S. Latino population.


Methodology: The study’s author, Jeffrey S. Passel, used the residual method to arrive at his estimate. Put simply, he subtracted the legal foreign-born population estimated in the Census Bureau’s March 2004 Current Population Survey (the sample was 50,000 households) from the number in its annual census. The difference between the two figures represents who wasn’t counted, that is, illegal immigrants. “The numbers are so large, I don’t see why anyone needs to exaggerate,” Passel said.


Estimate: 20 million as of January 2005


Source: Bear Stearns Asset Management, an equity and fixed-income investment management firm. Most of its assets belong to corporate clients.

Methodology: The authors of the estimate, Robert Justich and Betty Ng, contend that the census data used by Pew are incomplete. They buttressed that data by including the rate of growth in school enrollment, foreign remittances, border crossings and housing permits. “Demographers should see declines in school enrollment, but quite the contrary,” Justich said. “The demand for English-as-a-second-language programs is exploding at a much higher rate [than should be expected.]”


Estimate: 7 million as of January 2000 (20%)

Source: Immigration and Naturalization Services/Office of Immigration Statistics (reorganized and renamed the U.S. Citizenship and Immigration Services).

Methodology: The estimate was contained in a January 2003 report and has not been updated. Its starting point is the 2000 census estimate of 13.5 million foreign-born residents who arrived in the U.S. in the 1990s. The agency used its data on legally admitted immigrants, deportable aliens who were sent home and nonimmigrant residents to arrive at a legal immigrant population of 8 million. (Nonimmigrant residents represent 28 visa classifications, including immediate families of U.S. citizens or green-card holders, foreign journalists and their families, and victims of crimes such as human trafficking.) The difference between the census and legal population numbers -- 5.5 million -- is the estimated illegal population. The 7-million figure is the result of adding 1.5 million estimated to have entered the U.S. before 1990 and still here in 2000.


Estimate: At least 20 million as of January 2004

(over 60%*)

Source: The American Resistance, an independent coalition of citizens who seek stronger border security.


Methodology: The founder of the organization, D.A. King, disbelieves census data. “I know that illegal aliens won’t answer the door for the census-taker,” he said. The 20-million figure comes from Georgia state Sen. Sam Zamarripa, among others. Approximately 8,000 illegal immigrants are daily added to the total, a number based on the Homeland Security Department’s estimate that 10,000 illegal immigrants try to cross the border each day. The 8,000 figure results from subtracting the roughly one in three caught, then adding in-country immigrants estimated to overstay their visas who thereby become illegal.

*Bear Stearns and the American Resistance each dispute the census data.