At a busy housing construction project in Howard County one recent morning, Alex Hernandez, 24, shouted instructions in Spanish as his crew members hoisted a heavy foundation beam into place. ¶“This job is difficult and dangerous. You have to work hard and move fast and be careful,” said the stocky crew chief, an immigrant from El Salvador. “I have never seen an American do this work.” ¶At a Baltimore employment center, Keith Bellisaire, 40, proudly shared cellphone pictures of rooms he had painted on day jobs. He said he has not been able to land a full-time position in years. ¶“I’m ready to work, and I can work as hard as anyone. Sometimes I wonder if there is discrimination,” said Bellisaire, who is black. “I don’t think the Spanish people are trying to take away our jobs, but I wish I had more chances to show what I can do.” ¶In the battle over immigration reform, no issue is more contentious than whether low-skilled immigrants are displacing American-born workers or filling a vital economic gap by accepting jobs that many Americans are unwilling or unavailable to perform.

The dispute pits business owners, who claim that they cannot find enough Americans to clean rooms or hang drywall, against labor leaders who are trying to protect U.S. jobs and wages, and conservatives, who want to restrict legal immigration and punish undocumented immigrants.

On June 27, in a major compromise aimed at legalizing an estimated 11 million undocumented residents, the Senate passed an immigration bill that includes two new programs to raise the number of low-skilled foreign workers.

But when the House returns from recess next month, it is certain to reopen the divisive debate that almost scuttled the Senate effort. Business leaders are clamoring for more low-skilled visas, and labor groups are trying to limit them. Experts are updating reports to support arguments on both sides.

One report, published in June by the American Enterprise Institute and Immigration Works, found that immigrants today dominate the labor market in almost every job that entails a high level of danger, discomfort, repetition or extreme temperatures.

The state of U.S. immigration

See how immigration trends have shifted over the years.

Among U.S.-born workers, the report found that even those with low skills are twice as likely to work in offices or shops, and that less than 3 percent of those who are unemployed said they had worked as dishwashers or house cleaners or in similar jobs in the past five years.

On the other side, a study by the Center for Immigration Studies in July found that the number of employed Americans fell by 1.3 million since 2000, while the number of working immigrants rose by 5.5 million. With wages stagnating in immigrant-heavy occupations, the report concluded that immigrants are pushing Americans out of jobs they would be willing to do for higher wages.

The reality, however, is more complicated. According to some experts, the flood of Hispanic immigrant workers in the past 25 years — both legal and illegal — has had a much smaller effect on employment patterns than other trends, including factory flight overseas, weakened labor unions and a spate of recessions.

They also say that low-skilled immigration has been both a boon and a burden to America. It has squeezed public services but generated tax revenue. It has depressed wages in some areas but has revitalized ailing communities. The group that suffers most from the influx of new foreign laborers, these experts report, are earlier immigrants.

“We have to be honest here. Low-skilled immigration has costs, but it also has benefits,” said Harry Holzer, a professor of public policy at Georgetown University. While some individuals and locations can be harmed, he said, the positive impact on the U.S. economy is unquestionable. And if illegal immigrants are brought into the mainstream, he predicted, “the playing field will level out.”

‘A loyalty issue’

Maple Lawn, the housing development where Alex Hernandez works, offers one window on both the economic calculus and cultural attitudes that have transformed many workplaces and industries that employ growing numbers of low-wage immigrants.

One of the builders on the site is Mitchell & Best Homes. Many of its laborers, such as wood framers, are Latino, and site supervisor Michael Smith says the reason has more to do with work ethic than wages. Even at $20 per hour, he says, few U.S.-born workers apply.

“Americans want more money, and Spanish will take less, but I don’t care if they’re white, black, Spanish or women. We just want good workers,” Smith said. “There’s a loyalty issue, too. The white workers want to leave right at 4 p.m., whether or not the work is done. The Hispanics will stay on until it’s finished.”

Such comments are echoed by employers in other parts of the country. Jay Williams, vice president of a landscaping firm in Houston, said he advertises for 20 jobs each summer but that U.S.-born applicants usually quit after a few days. Without access to more temporary foreign workers, he said, such firms may resort to illegal immigrants. “We still need guys to dig holes and push wheelbarrows,” Williams said.

Andrew Puzder, head of the California-based Hardee’s fast-food chain, said his business is a good fit for immigrants because they are willing to start at the bottom and work up.

One of Puzder’s 70,000 U.S. employees is Jose Diaz, 31, who was born in Nicaragua and started frying burgers a decade ago in California. Today he manages a Hardee’s outlet in Stafford County, where his salary of about $40,000 is more than 12 times the per-capita income of his native land.

“Immigrants appreciate what America offers,” Puzder said during a recent visit to Washington to lobby for immigration reform. “They are not taking jobs from Americans, because there are not sufficient Americans applying for jobs. Maybe they feel they have better options.”

The Center for Immigration Studies, however, suggested that submissiveness rather than ambition makes low-skilled immigrants especially desirable. In a new report this month, it noted that many depend on their employers for visas and come from “docile, authority-fearing Third World populations,” making them easier to manage.

Still, immigrants’ acceptance of low wages remains a major part of their appeal to profit-minded companies. Some economists assert that the flood of Hispanic workers has flattened wages in an array of low-skilled jobs. In some industries such as construction, tradesmen complain that this has also allowed firms to bid down contracts for installing pipes, stairs or wiring.

“A job that used to pay me $2,500 now pays $1,200,” said Ron Vigil, 57, a carpenter from Manassas who builds custom staircases at Maple Lawn. “The Hispanics will do a job for less and they are happy, and corporate greed is a factor, too. It really affects people like me.”

Yet some academics say the cause and effect is not so clear-cut. According to Holzer, removing immigrants from the job market would not necessarily drive up wages to a level Americans today would accept — or companies would be willing to pay.

“Sure, that would add appeal,” Holzer said. “The problem is that if wages kept on rising, employers would start eliminating jobs, substituting technology and other norms of production. Immigration is really only one small factor.”

Effect on black workers

The U.S.-born workers most affected by low-skilled immigration are African Americans.

Many jobs once held by black Americans are now done by Hispanic immigrants, while black unemployment has reached 13.5 percent nationwide. One study at Harvard found that between 1960 and 2000, a 10 percent increase in immigrants in various jobs reduced black wages and employment by up to 4 percent.

But experts say there are other reasons why many low-skilled African Americans are out of the job market. One is the large number who become lost to street life, prison and the stigma of being an ex-offender. In the District, over half of about 66,000 ex-offenders are jobless.

According to Holzer, low-skilled black Americans may face added burdens of employer bias or may disconnect from formal education and employment systems at an early age — while immigrants make constant use of informal job grapevines.

Also, as a result of the civil rights movement, many African Americans feel they no longer have to accept demeaning work, even if they lack the skills to do better.

This is especially true of field work, for historical reasons. Immigrants — hungrier and less sensitive to social stigma — have jumped in to replace them.

When African Americans do take jobs in dirty or dangerous conditions, they are apt to ask for higher wages and better protections — just like other American workers — than immigrants may be in a position to demand.

Willie Lucas, 57, is a janitor and union officer at Howard University, where the once all-black maintenance staff is now mixed with Central Americans. He supports immigration reform and workplace diversity, yet he also joined a protest against a company that sent hundreds of Hispanic workers to take jobs in a poor, black area of the District.

“They said people didn’t want the jobs, so we marched to their office with thousands of applications from black men,” Lucas recalled indignantly. “Blacks want to work, too, but not to settle for any price. With all this history we went through . . . we have a sense of entitlement.”

Adama Garda, 43, a legal immigrant from Niger, has a very different perspective. On a recent morning, she was waiting at a job- placement center in Rockville, dressed neatly in a skirt and heels. She said that her last job as a health aide to disabled senior citizens had been unpleasant but that she would do it again in a minute.

“Americans don’t have the patience and fortitude for that kind of job, but I never say no,” Garda said. “They can always find something else, but we have no choice. I am an immigrant. Whenever I find something precious, I grab it.”

‘We’re all in the same boat’

Still, there are many black Americans, especially those who have been through personal and economic hardships, who insist that they are not too proud to haul furniture or work in kitchens. Some express resentment toward Hispanics, but others say they are learning to accept the newcomers and even identify with them.

Bellisaire, who was reading the sports pages while he waited at the Baltimore job center, said he wondered whether his prospects were being harmed by stereotypes that African Americans are not hard workers. Yet he said he had gotten over his initial discomfort at mingling with job seekers who don’t share his language or nationality.

“When I first walked in here and saw all these Spanish faces, I wondered how I would ever get a job,” he confided. But after months of seeing some of the same faces, with the same worry and disappointment, he feels differently.

“The way I see it,” Bellisaire said, “we’re all in the same boat.”