In my area many of the illegals are Peruvian and Ecuadoran, with some Central Americans as well. I know across the country the majority are Mexican, but eventually Mexico will run out of people to export; today 1/10 of all people born in Mexico already live in the US.
The bracero program is monitored/administered by our government (at least it used to be); I remember when schools were set up for their children during their seasons here. Americans will do any work when the wages are determined by true supply & demand; the agricultural sector simply skirts that to keep labor costs low. Long before Mexicans were swarming across the border, Americans worked as farmers all over this country.
I know.