I believe that illegal immigrants bring relatively little economic benefit and cause relatively little economic harm. I believe that there are substitutes readily available for the work done by illegal immigrants. Legal residents could do some of the work. Other labor could be replaced by capital or by alternative production techniques. By the same token, because there are many substitutes available for unskilled labor, the salvation of American workers does not lie in immigration restrictions.
I'm not sure how much of the political resonance comes directly from economics, though. I think there's a political aspect, too, having to do with the effort of people who aren't citizens, and aren't here legally, to wield political power within the United States. I think this has a particularly unfortunate resonance in light of recent events in Europe. It's not The Camp of the Saints, but I think it has overtones of that sort.
The 11 million illegal aliens in the nation pose little threat to national security. The 19 hijackers on Sept. 11 all were here legally. None were Mexican.
President Bush has done nothing about the mexican border. And for good reason. The Mexican border is not a problem. The economic refugees do cost Californians in social programs. But that is California's problems. California controls its state social programs. Let it change its rules (and judges, if that is a problem).