Complex sentence: The bracero program could not accommodate the number of Mexicans that wished to work in the United States, which resulted in those who were denied entry as a bracero illegally crossing into the US in search of better wages and opportunity.
Split into simpler sentences: The bracero program could not accommodate the number of Mexicans that wished to work in the United States. Many who were denied entry as a bracero crossed illegally into the US in search of better wages and opportunity.