I can't imagine what would happen to our economy if 12,000,000 workers were suddenly ripped out of it and deported. Personally, I don't want to pay $10 or $15 for a head of lettuce.
There sure aren't enough fat, lazy Americans willing to get off the couch to go do those jobs.
I imagine there would be quite a few farms and orchards closing down because of an inability to hire workers at a wage to keep food costs affordable. All of us have already seen price increases at the grocery store due to higher oil prices and we have taken the hit in our wallets.
Those increases would seem welcome compared to what would happen if we lost the workforce we currently have.