WASHINGTON -- The number of illegal immigrants living in the U.S. has dropped for the first time in two decades -- decreasing by 8 percent since 2007, a new study finds. The reasons range from the sour economy to Mexican violence and increased U.S. enforcement that has made it harder to sneak across the border.
Much of the decline comes from a sharp drop-off in illegal immigrants from the Caribbean, Central America and South America attempting to cross the southern border of the U.S., according to the Pew Hispanic Center, which based its report on an analysis of 2009 census data.
The findings come amid bitter debate over Arizona's strict new immigration law, which was passed earlier this year but is on hold while it is challenged in federal court. The Obama administration contends the state law usurps federal authority and promotes racial profiling, while Arizona leaders say states are justified to step in if federal enforcement falls substantially short.
The study released Wednesday estimates that 11.1 million illegal immigrants lived in the U.S. in 2009. That represents a decrease of roughly 1 million, or 8 percent, from a peak of 12 million in 2007.
The study puts the number of illegal immigrants down to about where it was in 2005. They still make up roughly 4 percent of the U.S. population.
The Homeland Security Department's own estimate of illegal immigrants is slightly lower, at 10.8 million. The government uses a different census survey that makes some year-to-year comparisons difficult.
An increase in unauthorized immigrants leaving the U.S., by deportation or for economic reasons, may have played a factor in the falling number.
In recent years, U.S. Immigration and Customs Enforcement has deported an increasing number of illegal immigrants, reaching a high last year of more than 389,000 people, according to government figures.
States in the Southeast and Southwest saw some of the biggest declines in the number of illegal immigrants from 2008 to 2009, including Florida, Nevada and Virginia. Arizona saw a decrease, but it was too small to be statistically significant.
It's hard to figure out how much of the decline to attribute to the bad economy and how much to federal immigration enforcement, said Jeffrey Passel, a senior demographer at Pew who co-wrote the analysis.
"They're certainly acting together," he said. Passel said illegal immigrants now find it more expensive and dangerous to cross into the U.S. and also have less incentive to do so given the languishing job market in construction and other low-wage industries.
The analysis found the sharpest decline -- 22 percent -- among illegal immigrants from Latin American countries other than Mexico. This may reflect a lesser-known aspect of the debate that broke into the news again last week when the bodies of 72 Central and South American migrants were found in a cartel stronghold in northern Mexico: Thousands of non-Mexicans disappear on their way to the U.S., falling victim to demands that they pay impossible ransoms to criminal gangs that control access to the U.S. border.
"While people are arguing the government is not stopping illegal immigration, our data suggests the flow of undocumented immigrants sneaking into the country has dropped dramatically," Passel said.