During the years when the United States offered a legal program for temporary guest workers, known as the Bracero Program, the number of illegal border crossings plummeted, from over a million per year to just a few hundred. After the program’s demise, illegal crossing skyrocketed – back to a million again.

“Illegal Immigrants and Guest Workers”

Mexican migration to the U.S. and apprehensions of illegal entrants, 1943-1978

Source: Select Commission on Immigration and Refugee Policy, Staff Report, 1981, p.471