Subsidized Mass Migration

What should be done with the estimated 15 million people living in the United States without the legal right to be here? It seems most politicians and many Americans come down on one or the other extreme. Many Republicans, including Republican presidential candidate Donald Trump, have the idea that they can round up 15 million people and ship them back to wherever they came from. Many Democrats, on the other hand, would grant them blanket amnesty, give them citizenship, and make sure as many as possible are fully signed up to the welfare ranks.

Has anyone thought for a moment about how difficult, expensive, disruptive, and dangerous to our civil liberties it would be to turn over every stone in this country to search for someone who might not be here legally? How