By holding down natural wage growth in labor-intensive industries, immigration serves as a subsidy for low-wage, low-productivity ways of doing business, retarding technological progress and productivity growth.

But the other audience, I think, is people in Central America because since last summer, they've been running ads down there - the United States government has - don't come, it's dangerous. You will be immediately deported. That's literally what it says in Spanish.

But the question is - are we deporting a couple hundred people for show or are we actually making a serious effort to remove everybody who's got a final order of removal? When I say enforcement theater, what I mean is a kind of pretend enforcement.

There's definitely a huge gap between the elite and public perceptions on immigration.

The interesting point is that the polarization is not so much among the public, although there's some of that. The polarization on the immigration issue is really between the elites and the public. In other words, this is not so much a right-left issue, which it is partly.

Assimilation is really a psychological process where you come to identify with a new country as yours. The ease of overseas travel and information access interferes with that.

But it's more an up-versus-down issue because the research has shown that opinion leaders, whether they're elected officials, journalists, business leaders - it's academics, religious leaders - they have dramatically different views on immigration. A