Esteban Torres was 3 years old when his father was sent back to Mexico by U.S. immigration authorities.

"One day, my father didn't come home," remembers Torres, who lived with his family in a mining camp in Arizona at the time. "My brother and I were left without a father. We never saw him again."

Torres, 85, who went on to become a congressman representing the Pico Rivera area, was part of a generation of people whose lives were changed dramatically by large-scale deportation campaigns during the 1930s, '40s and '50s in which millions of Mexican nationals were rounded up and sent across the border on buses, trains and ships.