Drum roll please… Increase the penalties for employers. People hire illegal immigrants because there’s no risk to them, only upside. Start raiding worksites and issuing heavy fines, and we’ll see how fast people stop hiring them. As soon as there’s no work here, people will stop risking their lives to get here. As long as there continues to be work here, people will do whatever it takes to get here, it’s as simple as that.
But no politician really wants to stop illegal immigration, it would hurt the economy. What they want is to appear tough on the issue.