Thirteen years ago, Bryan Hall began hiring migrant workers to pick crab meat from April to December. Now, he relies on 25 to 30 seasonal immigrant workers as the young locals he used to employ moved away.

Then, earlier this year, when the visas for seasonal workers were snatched up before Hall got his employees, he feared his seafood company, G.W. Hall & Sons, would go out of business.

It took an act of Congress, led by Maryland Democratic Sen. Barbara Mikulski, which allowed more seasonal worker visas to bring his employees back, some of whom have returned every year for 10 years.

Hall’s situation illustrates one side of the continuing debate about immigrant labor: Are immigrants taking American jobs, or are native workers unwilling to take on the low-paying arduous tasks often performed by immigrants? Even economists disagree on the issue.

One sentiment almost everyone agrees on is the United States needs immigrant labor, but there is no consensus on how much or in what way that affects native workers.

About 40 percent of foreign-born workers are from Mexico and Central America, according to a report by the Congressional Budget Office, and 75 percent of them work jobs requiring little education, including manufacturing and housekeeping. They represent the fastest-growing segment of the U.S. labor force.

It’s a fact that more Americans are finishing high school and becoming more qualified for higher-skilled positions, which creates a demand in the low-skilled workforce.

The influx of cheap immigrant labor could also be pushing Americans to finish high school because of the increased competition for low-skilled jobs, according to the CBO report.

Unskilled immigrant workers compete for work with other immigrants and Americans with little education, so the brunt of the impact is felt in the low-wage sector. Economists disagree as to whether an abundance of low-wage immigrant workers drive down wages for Americans in the same skill level.

Studies on the national level show cheap labor slightly depresses wages, but David Card, professor of economics at the University of California, Berkeley, found little if any effect on wages in cities and localized areas. The wages in locations with a high concentration of immigrants grew at the same rate as cities with low rates of immigration.

Additionally, without cheap immigrant labor, certain industries in this country would cease to exist, Card said, such as textile manufacturers and sugar beet farmers, because only the high-end companies could afford American workers.

“The economy is changing all the time,” Card said. “There are jobs that don’t exist here anymore.”

Just as the elevator operator has all but disappeared, so, too, would the hand car-wash without immigrant labor, he said. Many vineyards in California use hand-picked grapes to make wine, but “if there were no Mexicans, that would all be mechanized.”

Small town meat-packing plants, once staffed with unionized Americans, have become primarily immigrant workplaces, Card said. The shift probably occurred as Americans finishing high school in small towns where meat-packing is the only option moved to find better jobs in cities. American workers in that position have an advantage over immigrants with little education and no English ability.

The influx of unskilled workers in the United States can also be a good thing for consumers. The CBO report notes that a larg