Is ethnic diversity to blame for potholes?

Compared to Japan, Germany, Korea, the U.K., and France, America is not very good at providing public goods. Why? One reason might be geographic diversity. We're just so big and spread out that a LOT of bargaining is needed in order to get stuff done at the federal level, or even the state level. That bargaining is going to result in inefficiency even when we do agree to spend money.

But here's another reason: ethnic diversity. William Easterly, Alberto Alesina, and Jenina Matuszeski have found that in African countries, more ethnic diversity is correlated with governments that provide fewer public goods.