The study, which covers all immigrants, legal and illegal, and their U.S.-born children younger than 18, found that immigrants tend to make economic progress by most measures the longer they live in the U.S. but lag well behind native-born Americans on factors such as poverty, health insurance coverage and homeownership.
The study, based on 2010 and 2011 census data, found that 43 percent of immigrants who have been in the U.S. at least 20 years were using welfare benefits, a rate that is nearly twice as high as native-born Americans and nearly 50 percent higher than recent immigrants.
The report was released at a time when both major presidential candidates have backed policies that would make it easier to immigrate legally and would boost the numbers of people coming to the U.S.
Steven A. Camarota, the center’s research director and author of the 96-page study, said it shows that questions about the pros and cons of immigration extend well beyond the sheer numbers and touch on the broader consequences of assimilating a population defined by tougher socioeconomic challenges.
“Look, we know a lot of these folks are going to be poor, we get it. But don’t tell the public it’s all going great, which is the story line I think a lot of people want to sell,” Mr. Camarota said. “There is progress over time. Every measure shows improvement over time, but still, the situation does not look like we’d like it to look, particularly for the less-educated. They lag well behind natives even when they’ve been here for two decades, and that is very disconcerting.”
Federal law requires that the government deny immigrant visas to potential immigrants who are likely to be unable to support themselves and thereby become public charges.
On Tuesday, a handful of Republican senators wrote to the Homeland Security and State departments asking them to explain why they don’t consider whether potential immigrants would use many of the nearly 80 federal welfare programs when they evaluate visa applications.
Neither department responded to messages Tuesday seeking a response to the senators’ letter.
Expanding legal immigration is a contentious issue for voters, the vast majority of whom tell pollsters that they want the levels either retained or decreased.
But most politicians want legal immigration expanded.
During his time in the U.S. Senate, Barack Obama backed bills that would have dramatically boosted legal immigration, potentially by hundreds of thousands a year. As president, he has called for the same thing.
“We need to provide our farms a legal way to hire workers that they rely on, and a path for those workers to earn legal status. And our laws should respect families following the rules — reuniting them more quickly instead of splitting them apart,” Mr. Obama said in a major speech on the subject in El Paso, Texas, in 2011.
His presumed Republican challenger, Mitt Romney, in June called for increasing legal immigration for students who study in high-tech fields and admitting unlimited family members of those who hold green cards.
“Our immigration system should help promote strong families as well — not keep them apart. Our nation benefits when moms and dads and their kids are all living together under the same roof,” Mr. Romney told the National Association of Latino Elected and Appointed Officials.
Mr. Camarota’s report took a broad look at the immigrant population and found that immigrants are contributing to major changes in American society, including that one-fourth of public school students now speak languages other than English at home.
It also found that immigrants as a population lead complex economic lives that aren’t easily put into one category or another.
Immigrants made up more than half of all farmworkers, 41 percent of taxi drivers and 48 percent of maids and housecleaners, but they also represented about one-third of all computer programmers and 27 percent of doctors.
The statistics varied greatly by geography. In Massachusetts, native-led households averaged $89,000 in income while immigrant households averaged $66,000.
In Virginia, immigrant-led households averaged $93,000 in income, far outstripping native households’ $80,000 average. Likewise, immigrant families averaged a larger tax burden in Virginia — though they also had higher rates of use of welfare or Medicaid.
The center found that use of public benefits varied dramatically based on where immigrants originated.
Mexicans were most likely to use means-tested benefit programs, with 57 percent, while 6 percent of those from the United Kingdom did. The rate for native-born Americans is 23 percent.
Mr. Camarota said a key dividing line is educational attainment. Immigrants who have been in the U.S. 20 years and who have bachelor’s degrees or higher make slightly more than the average native-born American. But immigrants with only high school educations make less no matter how long they have been in the U.S.
“The fact is the less-educated in particular — they don’t do well over time,” he said. “It’s not reasonable to expect an immigrant who comes to America with only a high school education to close the gap with the native-born.”
Scholars debate whether the current wave of immigrants will assimilate differently from those in the 1800s and at the start of the 20th century.
George Borjas, a Harvard University professor, has argued that second-generation Americans — the children of today’s immigrants — will fall behind in wages by about 10 percent by 2030.
But in “Assimilation Tomorrow,” a report released in November, Dowell Myers and John Pitkin said immigrants of the 1990s eventually will attain high rates of homeownership and 71 percent will become U.S. citizens by 2030.
Those authors said immigrants were set back by the recent recession but were still on track to follow the same assimilation path as previous waves of immigrants.
They also said a program to legalize the estimated 11 million illegal immigrants in the U.S. would be critical to helping assimilation.