Thanks to David for his very kind words. I've enjoyed my EconLog stint and will resume more regular writing for Forbes.com as well as a new gig with DepositAccounts.com in January. This isn't quite my last post; that will be published later today.
In response to my post "Immigrants and their Motivations," a reader directed me to this post in which Tyler Cowen notes that immigrants aren't as libertarian as natives.
This strengthens but does not save the case for restricting immigration. As Bryan has pointed out several times, restricting immigration is itself a restriction of liberty. I also suspect that in light of Alesina et al.'s result on ethnic heterogeneity and welfare states, a libertarian immigration policy will make reduce support for the welfare state. Finally, Bryan's student (and David's co-author) Zachary Gochenour is working on a dissertation about the political externalities from immigration; in a working paper, he and Alex Nowrasteh showing that "this fear is largely unfounded."
tl;dr: More immigrants might mean less liberty on some margins, but restricting immigration itself violates liberty. I think we would be freer on net with easier immigration.