A sharp decline in the U.S. population of unauthorized immigrants that accompanied the 2007-2009 recession has bottomed out, and the number may be rising again, according to a new preliminary Pew Research Center estimate based on U.S. government data.As of March 2012, 11.7 million unauthorized immigrants were living in the United States, the report stated. The estimated number of unauthorized immigrants peaked at 12.2 million in 2007 and fell to 11.3 million in 2009, breaking a rising trend that had held for decades. Among other findings of the survey:—California remains the state with the largest unauthorized immigrant population, but its share of the total is sharply less than it was 20 years ago.—Mexico remains the country from which the most unauthorized immigrants come to the U.S., but there are 15 percent fewer Mexicans here than there were five years ago.The report was compiled by Pew Center staff members Jeffrey Passel, a senior demographer; D’Vera Cohn, a senior writer; and Ana Gonzalez-Barrera, a fellow of the Transatlantic Forum on Migration and Integration.Although there are indications the number of unauthorized immigrants may be rising, the 2012 population estimate is the midpoint of a wide range of possible values and in a statistical sense is no different from the 2009 estimate.The report stated that different trends appear among the six states in which 60 percent of unauthorized immigrants live: California, Florida, Illinois, New Jersey, New York and Texas. Of these, only Texas had increases but no decrease in its unauthorized immigrant population over the 2007-2011 period. The other five states (and the balance of the country) all experienced peak numbers of unauthorized immigrants in 2007 followed by declines over the next year or two.“These six states,” the researchers noted, “have long been home to the majority of the nation’s unauthorized immigrant population, but as foreign-born residents have moved into new destinations, the six are not as dominant as they once were. In 2012, 60 percent of the unauthorized immigrant population lived in those states, compared with 80 percent in 1990.”Most of this reduction in share in the largest states, the report said, “is due to a sharply reduced proportion in California. The Golden State had 21 percent of unauthorized immigrants in 2012, compared with 42 percent in 1990.”California’s unauthorized immigrant population was 2.45 million in 2012, a decline from a peak of 2.8 million in 2007. After two years of decreases in 2008-09, the decline stopped in 2010 and 2011 but did not change to an increase. (No breakdown was available on immigrant population change by individual county.)While the total number of unauthorized immigrants living in these six large states was 2¬Ω times as high in 2012 (7.0 million) as in 1990 (2.8 million), the total in the remaining states and the District of Columbia was nearly seven times as high in 2012 (4.7 million) as it was in 1990 (700,000).In terms of country of origin, the post-2007 population dip was even sharper among Mexicans (who made up 52 percent of 2012 unauthorized immigrants) than the overall population decrease, although the Mexican decline appears to have stopped after 2010. In 2012, 6.05 million Mexican unauthorized immigrants were in the U.S., a decline of about 900,000 from 2007, though a significant gain from 1.4 million in 1990. Mexico’s share of the unauthorized immigrant population had been 57 percent in 2007.The number of unauthorized immigrants from countries other than Mexico continued to rise, reaching 5.7 million in 2012, the third straight year of increase (the number was 2.1 million in 1990).Researchers noted that changes in the size of the unauthorized immigrant population result from the balance of inflows of new unauthorized immigrants offset by departures from the U.S. (and deaths, which are relatively few). “Several other data sources also provide evidence of reduced arrivals of new Mexican immigrants, especially unauthorized immigrants,” the researchers said. “U.S. Customs and Border Patrol apprehensions of Mexicans attempting to enter the U.S. illegally across the southern border help to explain some of the trends in the unauthorized Mexican population. While the apprehensions do not themselves measure the number of illegal border crossers, they are an indicator of changing flows.”During years when the unauthorized Mexican population was increasing rapidly, annual apprehensions of Mexicans were almost always close to 1 million or more, peaking at more than 1.6 million in fiscal 2000, the researchers pointed out. Apprehensions began to drop significantly in fiscal 2007 and by 2011 were only about one-sixth of their peak value (286,000 versus 1.64 million). The apprehensions of Mexicans decreased further in 2012, to 266,000.To view the complete Pew Research Center report, visit http://www.pewhispanic.org/files/2013/09/Unauthorized-Sept-2013-FINAL.pdf.{gallery width=100 height=100}gallery/2013/0927/immigration/{/gallery}