Unauthorized Aliens Residing in the United States: Estimates Since 1986 [September 22, 2011] [open pdf - 473KB]
"Estimates derived from the March Supplement of the U.S. Census Bureau's Current Population Survey (CPS) indicate that the unauthorized resident alien population (commonly referred to as illegal aliens) rose from 3.2 million in 1986 to 11.2 million in 2010. Jeffrey Passel, a demographer with the Pew Hispanic Research Center, has been involved in making these estimations since he worked at the U.S. Bureau of the Census in the 1980s. 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. The estimates of unauthorized aliens peaked at an estimated 12.4 million in 2007. About 39% of unauthorized alien residents in 2010 were estimated to have entered the United States in 2000 or later. Similarly, the Department of Homeland Security's Office of Immigration Statistics (OIS) reported an estimated 10.8 million unauthorized alien residents as of January 2010, up from 8.5 million in January 2000. The OIS estimated that 6.6 million of the unauthorized alien residents were from Mexico, an estimate comparable to Passel and D'Vera Cohn's calculation of 6.5 million. The OIS based its estimates on data from the U.S. Census Bureau's American Community Survey. The OIS estimated that the unauthorized resident alien population in the United States increased by 37% over the period 2000 to 2008, then leveled off in 2009 and 2010. Research suggests that various factors have contributed to the ebb and flow of unauthorized resident aliens, and that the increase 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. Accordingly, the economic recession that began in December 2007 may have curbed the migration of unauthorized aliens, particularly because sectors that traditionally rely on unauthorized aliens, such as construction, services, and hospitality, have been especially hard hit."
CRS Report for Congress, RL33874