By Jennifer Medina

Feburary 1, 2012 -- CLAREMONT, Calif. — The dining hall workers had been at Pomona College for years, some even decades. For a few, it was the only job they had held since moving to the United States.

Then late last year, administrators at the college delivered letters to dozens of the longtime employees asking them to show proof of legal residency, saying that an internal review had turned up problems in their files.

Seventeen workers could not produce documents showing that they were legally able to work in the United States. So on Dec. 2, they lost their jobs.