One Money, One Market: A Revised Benchmark

The introduction of the euro generated substantial interest in the impact of currency unions (CUs) on trade flows. Initial estimates suggested a tripling of trade, which gave rise to a literature in search of "more reasonable" CU effects. Theoretical derivations of the gravity model highlight, however that the CU literature neglects to control simultaneously for general equilibrium effects (multilateral resistance) and unobserved bilateral heterogeneity among trade partners. Once we introduce the appropriate controls, CU trade effects are shown to range around 50%. We also highlight that the practice of reporting average CU effects generates misleading results. The average effect is shown to be a composite of disparate individual CU effects ranging from 40% (euro) to about 100% (Central African franc).