Jonah: Yes, there is an equivalent of the Kuznets Curve for migration, though there hasn’t but much, if any, quantitative research on it. Ag economist Phil Martin, one of the top guys around on immigration, has named it the Migration Hump (I know, sorry), with pressure for emigration on the vertical axis and the level of development on the horizontal, so that migration pressure increases with increased development, then tapers off at some point. Phil’s website is here and he writes about the Migration Hump here.

We don’t have any idea when Mexico, for instance, might pass over the Migration Hump, though the Mexican government doesn’t seem to think it will happen any time in the next 50 years (see here). The policy problem is that people promoting NAFTA, CAFTA, etc. often say that these measures will alleviate our immigration problems in an unspecified, but relatively short, period of time. In fact, NAFTA, CAFTA, etc. increase our immigration problems, at least for a while – which is why such measures (which I’m generally in favor of) need to be (but never are) accompanied by dramatically increased immigration controls and provisions for the newly mobile peasants of the sending countries to move to their own cities, instead of ours.