The report by the Pew Research Center, prepared from government figures, offers an X-ray of the displacement of undocumented immigrants during and after the Great Recession.
In 2009, the undocumented immigrants in the US totalled 11.3 million.
The new estimate was released as pro-immigrant groups are continuing a campaign in favour of immigration reform that would permit the legalisation of undocumented foreigners.
The US senate, which is under Democratic control, on June 27 approved the reform, but it is given zero chance of passing in the Republican-dominated House of Representatives, though some GOP lawmakers have said that they would be ready to approve individual bills dealing with each aspect of illegal immigration.
The undocumented population in the US reached 12.2 million in 2007, but declined by nearly a million during the worst of the recession.
Pew made it clear that the ranks of legal immigrants have continued to increase in recent years, and the undocumented immigrants represent 28 percent of the foreign-born population, down from 30 percent in 2007.
The report found that 60 percent of the undocumented people continue to live in six states: California, Florida, Illinois, New Jersey, New York and Texas.
The report also says that the number of detentions of undocumented people by the Border Patrol increased steadily during the 1990s and peaked at 1.7 million in fiscal year 2000.
After a slight decline between 2001 and 2007, the number of detentions fell drastically between 2007 and 2011.
--IANS (Posted on 24-09-2013)