Lately I’ve been delving more deeply into the empirical evidence on the political externalities of immigration.  Two striking graphs from Alesina, Glaeser, and Sacerdote’s “Why Doesn’t the United States Have a European-Style Welfare State?” (BPEA 2001):

1. Internationally, racially diverse societies have much smaller welfare states, controlling for GDP per capita, regional dummies, and more.  The bivariate relationship:


(Large version)

2. Within the U.S., states with higher black population shares have smaller welfare benefits, controlling for income:


AGS’s story is precisely the one I’ve been pushing: Diversity undermines solidarity.  People don’t mind paying high taxes to support people “like them.”  But free money for “the other” leads to resentment and political pushback.  If you’re a social democrat, this implies a tragic trade-off between social justice for natives and social justice for potential immigrants.  But if you’re a libertarian, the opposite is true.  The welfare state doesn’t make open borders impossible.  It’s open borders that makes the eventual abolition of the welfare state imaginable.