In federations with a multi-dimensional public sector, externalities m
ay originate in the private sector (private sector externalities) or i
n the local public sector (public sector externalities). It is well es
tablished that correction of public sector externalities will require
a central authority, We show that with only private sector externaliti
es, local government equilibria are efficient. We thus have a simple r
ule for the assignment of corrective policies to levels of government.