Yes, the vast amounts of money destabilize the Central American countries and cause corruption and crime, and that's why the invaders can't help coming here.
Of course being the Libertarian Bible, they also sneak in a little hint that the baddy old war on drugs is also to blame.
Oh yes, and the obligatory gibe at conservatives going nutso on the issue.
Ask me why I even read these papers.
This being a Sowell thread, here's what the good Doctor says on that subject: http://www.freerepublic.com/focus/chat/2768055/posts.