As tide of illegal immigrants goes home,will U.S. Economy Suffer?

In the more than a dozen states that require businesses to confirm
employment eligibility through the Internet-based federal program E-Verify,
employers are in a corner. "The em-ployers just really don't have an
option," Ms. Whitley says. She adds that the farm labor workforce is 75
percent illegal.

Whitley has noticed growing interest in the H-2A visa program that
brings in temporary seasonal farmworkers. But many employers still shun
these visas, saying the program – which requires housing provisions and
set wages – is too bureaucratic and costly. Advocacy groups long have
maintained the program is fraught with employer abuse.

Massey says
spot shortages are possible in sectors that employ large numbers of
Mexican workers, particularly agriculture, but he believes that a
gradual shift toward the use of guest workers may offset any potential
labor deficiencies.

Mexicans in growing numbers are securing visas
that allow them to hold temporary US jobs legally, says Massey. "The
workers that are coming into the United States are not just agricultural
workers, they're workers in the non-agricultural sector, and
increasingly, they're skilled workers."

The US State Department
reports a 53 percent increase in temporary visas for seasonal farm work
issued between 2006 and 2010. And other visa categories are driving the
expansion, too, including those for professional health and technology
workers under the North American Free Trade Agreement.

But even with the visas, the farm labor situation suffers, says David Dyssegaard Kallick, a senior fellow at the Fiscal Policy Institute, a nonpartisan think tank in New York. "Those jobs really do seem to go begging when immigrants are pushed out, at least temporarily."

In
the long run, Mr. Kallick says, the US labor market probably would
adapt: "Maybe wages and working conditions would go up enough to make
the jobs more attractive, or maybe some farms would close up shop.
Basically, though, I don't think dishes wouldn't be washed in
restaurants without immigrants to do it."

He says the flow of immigrants will return when the demand for workers is back, although "we're not anywhere near there" yet.

"As
long as the large wage differences between Mexico and the US exist,
there will be incentives for people to endure the real risks of crossing
illegally," says Judith Gans, manager of an immigration policy program
at the University of Arizona in Tucson. She says that as jobs do become available, the pressure on the border will correspondingly increase.

In
the long term, the changes in Mexico and shifts in migration in all of
Latin America may ease the pull north of the border, Ms. Gans adds.

The
impact of fewer illegal immigrants coming into the US will depend on
how long it takes for the economy to bounce back, says Audrey Singer, a
senior fellow at the Brookings Institution, a Washington public policy group.

"In
the intervening time, a lot can happen in a place like Mexico, where
unemployment is relatively low right now," she says. "Birthrates have
dropped and the demand for workers has been rising. For young people
entering the workforce, it may mean more opportunities and less reason
to leave."

• Sara Miller Llana contributed to this article from Mexico City.