The nation's undocumented immigrant (search) population surged to 10.3 million last year, spurred largely since 2000 by the arrivals of unauthorized Mexicans in the United States, a report being released Monday says.
The population of undocumented residents in the United States increased by about 23 percent from 8.4 million in the four-year period ending last March, according to the analysis of government data by the Pew Hispanic Center (search), a private research group.
That equates to a net increase of roughly 485,000 per year between 2000 and 2004. The estimate was derived by subtracting the number of unauthorized immigrants who leave the United States, die or acquire legal status from the number of new undocumented immigrants that arrive each year.
The prospect of better job opportunities in the United States than in their native countries remains a powerful lure for many immigrants, said Pew center director Roberto Suro, pointing to a reason often cited by other researchers.
"The border has been the focus of federal efforts (to cut illegal entry) and has not produced a reduction in flow. Certainly that's an indication of ongoing demand," he said.
The population is growing at a similar pace as in the late 1990s even though the U.S. economy today isn't as robust, Suro said.
Assuming the flow of undocumented immigrants into the country hasn't abated since March 2004, the population is likely near 11 million now.
The report considered "undocumented" immigrants primarily as those here illegally; those in the United States on expired visas; or those who violated the terms of their admission in other ways.
Also included are a small percentage of immigrants who may have legal authorization to be in the United States, including those with temporary protected status and those applying to seek asylum.
Mexicans by far remain the largest group of undocumented migrants at 5.9 million, or about 57 percent of the March 2004 estimate. Some 2.5 million others, or 24 percent, are from other Latin American countries.
Overall, the U.S. foreign-born population, regardless of legal status, was 35.7 million last year. Those of Mexican descent again comprised the largest group -- more than 11 million, or 32 percent.
Controlling the flow of immigrants over the porous U.S.-Mexico border will be a central topic of discussion when Mexican President Vicente Fox (search) meets with President Bush in Texas on Wednesday.
The number of U.S. residents with Mexican backgrounds has increased by nearly 600,000 annually since 2000, with more than 80 percent of the new arrivals here with proper documentation, the Pew center estimated.
Secretary of State Condoleezza Rice and other government officials have raised concerns about border security amid recent intelligence that Al Qaeda (search) terrorists have considered using the Southwest border to infiltrate the United States.
Bush, meanwhile, has also promoted a guest-worker program that would allow migrants to work in the United States for a limited time as long as they have a job lined up.
Critics of the plan argue that such workers drive down wages because they often work for lower pay and fewer benefits that native-born residents.
"The best way to approach this is attrition by enforcement -- better enforcement of the borders and of worksites," said Steve Camorata of the private Center for Immigration Studies (search).
The Pew report found undocumented immigrants increasingly fanning out beyond longtime destination for foreign-born residents. In 1990, 88 percent of the undocumented population lived in six states -- California, New York, Texas, Illinois, Florida and New Jersey.
By 2004, those states accounted for 61 percent of the nation's undocumented population. The top state is California, where nearly one-quarter of the undocumented reside, followed by Texas (14 percent) and Florida (9 percent).
Next on the list were New York (7 percent), Arizona (5 percent), Illinois (4 percent), New Jersey (4 percent), and North Carolina (3 percent).
Arizona and North Carolina are two of the fastest-growing states in the nation overall and have metropolitan areas booming with new construction, restaurants and service-oriented businesses -- job sectors that often hire undocumented workers.