Common currencies affect trading costs and, thereby, the amounts of trade, output, and consumption. From the perspective of monetary policy, the adoption of another country's currency trades off the benefits of commitment to price stability (if a committed anchor is selected) against the loss of an independent stabilization policy. We show that the type of country that has more to gain from giving up its own currency is a small open economy heavily trading with one particular large partner, with a history of high inflation and with a business cycle highly correlated with that of the potential “anchor.” We also characterize the features of the optimal number of currency unions.

We present a model that links heterogeneity of preferences across ethnic groups in a city to the amount and type of public goods the city supplies. We test the implications of the model with three related data sets: U. S. cities, U. S. metropolitan areas, and U. S. urban counties. Results show that the shares of spending on productive public goods—education, roads, sewers and trash pickup—in U. S. cities (metro areas/urban counties) are inversely related to the city's (metro area's/county's) ethnic fragmentation, even after controlling for other socioeconomic and demographic determinants. We conclude that ethnic conflict is an important determinant of local public finances.