Highly skilled temporary and permanent immigrants in the United States now outnumber lower-skilled ones, marking a dramatic shift in the foreign-born workforce that could have profound political and economic implications in the national debate over immigration.

This shift in America’s immigration population, based on census data, is summarized in a report released Thursday by the Brookings Institution. It found that 30 percent of the country’s working-age immigrants, regardless of legal status, have at least a bachelor’s degree, while 28 percent lack a high school diploma.

The shift had been in the works for the past three decades, a period that has seen a dramatic increase in the population born outside the United States. But in 2007 the percentage of highly skilled workers overtook that of lower-skilled workers.

The trend reflects a fundamental change in the structure and demands of the U.S. economy, which in the past decades transformed from an economy driven by manufacturing to one driven by information and technology. The report also offers a new perspective on the national immigration discourse, which tends to fixate on low-skilled, and often illegal, workers.

“Too often the immigration debate is driven by images on television of people jumping over fences,” said Benjamin Johnson, executive director of the American Immigration Council, an immigrant advocacy organization. “The debate has been stuck in the idea that it’s all about illegal and low-skilled workers.”

Steven Camarota, director of research at the Center for Immigration Studies, an organization that advocates for tighter immigration restrictions, said the report raises other concerns.

“It seems, based on this and other studies, that we’ve got an oversupply of highly skilled workers coming into this country,” he said, adding that the study’s findings were not surprising. “New college graduates are faring very poorly on the labor market, and what the report is telling us is that we’re bringing in a high number of workers to compete with them.”

The study based its findings on the 2009 American Community Survey, administered by the Census Bureau, as well as data from the bureau’s Current Population Survey that date from 1980.

As the number of working-age immigrants in the United States has swelled, from 14.6 million in 1994 to 29.7 million in 2010, the numbers of highly skilled and lower-skilled immigrants have risen, but the highly skilled sector has risen faster, according to the report. Among the causes are the recent rise in the number of international students and of temporary H-1B visas, for which a bachelor’s degree is usually required, the report said.

The shift accelerated in the past decade, with nearly a third of working-age new arrivals in the 2000s coming with college degrees, the report said.

The report found that immigrants’ skill levels varied in different geographic locations, with coastal cities and established “gateway” metropolitan areas attracting more highly skilled immigrants, while areas near the U.S.-Mexico border draw more low-skilled immigrants.

Workers from Mexico and Central America tend to be lower skilled, while India, China and the Philippines send many more highly skilled workers than lower-skilled one, said Audrey Singer, a senior fellow at Brookings who co-wrote the study.

With its universities, international agencies, hospitals and technology companies, the Washington metropolitan area is one of the top magnets for educated immigrants, with 189 highly skilled immigrant workers for every 100 lower-skilled ones, according to the study.

“D.C.’s pretty diverse in terms of skills they’re bringing in and where they’re coming from,” Singer said.

Other high concentrations of college-educated immigrants include San Jose and Seattle.

The study also found that half of highly skilled immigrants in the United States are working in jobs for which they are overqualified.

“Education credentials and language are big hurdles,” said Matthew Hall, a University of Illinois sociology professor who co-wrote the report.

Many immigrants find their degrees and certifications from abroad are not recognized here.

Luma Ghalib, 42, trained as a doctor in her native Iraq and then went to New Zealand for more training. When she moved to the United States a decade ago, she had to start from scratch.

“When you come here, you know it’s not going to be easy,” she said, adding that she spent several years redoing her basic medical training and retaking exams in the United States before specializing in endocrinology.

The Fredericksburg resident said she has no regrets about the five additional years of study that allowed her to live and work as a doctor here.

“It’s a fair country, unlike a lot of countries,” she said. “If you’re a hardworking person, you get to where you need to be going.”

Some employers may say they prefer immigrants to native-born workers. When Samir Kumar needs to hire employees for his Northern Virginia-based IT business, he often looks overseas. Not only do workers from India and Ukraine have the required training, but their expectations are lower, he said.

“They actually don’t demand a very high amount of salary, and the expectations are kind of grounded and they don’t jump around so much” between companies, said the 39-year-old Ashburn resident, an immigrant from India. U.S.-born technology and business analysts are hard to find and hard to retain, he said, while immigrants with the same skills and education “are much easier to manage.”