How Many Immigrants Are Living in the United States Illegally?

Report Concludes Number is Shrinking

US Border Patrol agent carries immigrant child on Tex-Mex border
U.S. Agents Take Undocumented Immigrants Into Custody Near Tex-Mex Border. John Moore / Getty Images

The number of immigrants living in the United States illegally is shrinking, according to a Pew Hispanic Center report published in September of 2010.

The nonpartisan research group estimated that there were 11.1 million unauthorized immigrants living in the country as of March 2009.

That's about 8 percent fewer than the peak of 12 million in March of 2007, the Pew Hispanic Center reported.

“The annual inflow of unauthorized immigrants to the United States was nearly two-thirds smaller in the March 2007 to March 2009 period than it had been from March 2000 to March 2005,”  noted the report.

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Researchers estimated that the number of immigrants sneaking across the border every year has been declining, to ​an average of 300,000 in each of the years 2007, 2008 and 2009.

That's down sharply from an estimated 550,000 illegal immigrant crossing over a year in 2005, 2006 and 2007, and a whopping 850,000 a year in the first half of the decade.

Why the decline?

Researchers cite two possible reasons for the decline in illegal immigration: Tougher enforcement and the poor jobs market in the United States during the deepening great recession of the late 2000s.

"During the period covered by the analysis, there have been major shifts in the level of immigration enforcement and in enforcement strategies, as well as large swings in the U.S. economy," the Pew Hispanic Center noted.

"The U.S. economy entered a recession late in 2007, at a time when border enforcement was increasing. Economic and demographic conditions in sending countries and strategies employed by potential migrants also change," the report noted.

Portrait of Unauthorized Immigrants

According to the Pew Hispanic Center study:

  • Immigrants living in the United States illegally made up 28 percent of the nation's foreign-born population in 2009, down from 31 percent in 2007.
  • The number of immigrants sneaking in from Mexico accounted for 60 percent of unauthorized immigrants in 2009, or 6.7 million people. Other Latin American nations accounted for 20 percent, or 2.2 million people. South and East Asia accounted for 11 percent of the total, or 1.2 million people.
  • Most of the illegal immigrants living in the United States - 59 percent - lived in just six states in 2009: California, Texas, Florida, New York, Illinois and New Jersey. That's down, however, from 80 percent in 1990.
  • Nearly half of the immigrants living in the country illegally in 2009 - 47 percent or 5.2 million people - came here in 2000 or later.
  • The number of male immigrants living in the United States illegally dropped to 5.8 million in 2009 from a peak of 6.3 million in 2007. The number of female immigrants here illegally stayed flat over the same time period, at 4.2 million.
  • The number of children who are living here illegally was 1.1 million in 2009, down slightly over the decade.

“The recent decrease in the unauthorized population has been especially notable along the nation’s Southeast coast and in its Mountain West, according to the new estimates,” stated the report. “The number of unauthorized immigrants in Florida, Nevada, and Virginia shrank from 2008 to 2009. Other states may have had declines, but they fell within the margin of error for these estimates.”

Historic Estimates of Unauthorized Immigrants

Here is a look at the estimated number of unauthorized immigrants living in the United States over the years.

  • 2009 - 11.1 million
  • 2008 - 11.6 million
  • 2007 - 12 million
  • 2006 - 11.3 million
  • 2005 - 11.1 million
  • 2004 - 10.4 million
  • 2003 - 9.7 million
  • 2002 - 9.4 million
  • 2001 - 9.3 million
  • 2000 - 8.4 million
  • 1990 - 3.5 million