1950s: There is almost no literature that documents the experience of Chicano farm workers.

Today: The works of Rivera, which chronicle the life of the Chicano migrant worker, are widely read and studied in many universities in the United States.

1950s: Although accurate estimates are difficult, there are about 600,000 migrant workers in the United States yearly.

Today: Estimates of the number of migrant workers of all ethnicities (mostly Mexican Americans, Mexicans, African Americans, Puerto Ricans, and Native Americans) who work in the United States range from 125,000 to over one million.

1950s: Under the Bracero program, the United States legally admits 400,000 Mexican farm workers each season. Levels of illegal immigration from Mexico are not high enough to cause concern.

Today: Many regard soaring levels of illegal immigration from Mexico as a major security problem for the United States. In 2001, a panel reporting to President George...