From a reader:

I thought NAFTA was supposed to dampen those root causes! I remember that argument being used to generate support for NAFTA. What happened with that, eh? Is NAFTA not working as advertised?And from another:
Would we actually do Mexico a disservice by using “CIR” [comprehensive immigration reform] to take their workers who are fed up enough or hungry enough to leave? Would the lack of a US outlet move Mexico to reform more quickly?

[Me] Yes, it would; we are, in effect, defending the prerogatives of the Mexican ruling class by taking potential troublemakers off their hands. See here for some of the ways Mexico’s elite has feathered its nest while neglecting its responsibilities.