Estimating the Unauthorized Immigrant Population in the United States A Review of the “Residual Method” Used by the Department of Homeland Security Office of Immigration Statistics Presentation for the joint UNECE/Eurostat Work Session on Migration Statistics, Geneva, 3-5 March 2008

Estimating the Unauthorized Immigrant Population in the United States Annual estimates produced by the Office of Immigration Statistics (OIS), part of the Department of Homeland Security (DHS) OIS uses a “residual method” and American Community Survey (ACS) and DHS administrative data 11.6 million unauthorized immigrants, with 6.6 million from Mexico, as of January 1, 2006

The “Residual Method” To derive the unauthorized immigrant population, OIS estimates two populations: –Total foreign-born population (as of January 1, 2006) –Legally resident population (as of January 1, 2006) The unauthorized immigrant population is assumed to be the difference (i.e., residual) of the two.

Data Sources American Community Survey (ACS) –Annual nationwide household survey conducted by the U.S. Census Bureau –Data derived by OIS from the 2005 Public Use Micro-Data Sample Files (PUMS Files) DHS Administrative Data –Internal administrative records including: Legal permanent residents (LPRs) Refugees Asylees

Estimating the Foreign-Born Population 1.Foreign-born population that entered between 1980 and 2005 (ACS data) minus 2.Foreign-born population born in Cuba that entered between 1980 and 2005 (ACS data) plus 3.Estimate of the increase in the foreign-born population from July 1, 2005 to January 1, 2006 plus 4.Estimate of the foreign born living in group quarters plus 5.Estimate of the undercount of nonimmigrants in the ACS (10 percent) plus 6.Estimate of the undercount of LPRs, refugees, and asylees in the ACS (2.5 percent) plus 7.Estimate of the undercount of unauthorized immigrants in the ACS (10 percent) equals Estimated total foreign-born population as of January 1, 2006

Estimating the Legally Resident Population 1.LPRs who entered between 1980 and 2005 (administrative data) plus 2.Estimate of refugees/asylees who entered between 1980 and 2005 and had not adjusted to LPR status as of January 1, 2006 minus 3.Estimate of mortality of LPRs, refugees, and asylees minus 4.Estimate of emigration of LPRs, refugees, and asylees plus 5.Estimate of nonimmigrant population as of January 1, 2006 (administrative data) equals Estimated legally resident population as of January 1, 2006

Estimating the Unauthorized Immigrant Population (as of January 1, 2006) Foreign-born population 29,170,000 Legally resident population minus17,620,000 Unauthorized immigrant population 11,550,000 Largest countries of birth: Mexico (6.6 million), El Salvador (0.5 million), Guatemala (0.4 million) Largest states: California (2.8 million), Texas (1.6 million), Florida (1.0 million)

For More Information Michael Hoefer Director Office of Immigration Statistics Phone: or Website: