In the 1990s it was widely agreed that neither Europe nor the United States satisfied the conditions for constituting an optimum currency area, although the U.S. came closer (Bayoumi and Eichengreen 1993). Moderating this concern about Europe was the fact that it was possible to distinguish a regional core and periphery. Using updated data, we confirm that the United States remains closer to an optimum currency area. More intriguingly, the Euro Area shows striking changes in correlations and responses. We interpret these as reflecting hysteresis with a financial twist, in which the financial system causes aggregate supply and demand shocks to reinforce each other. An implication is that the Euro Area needs vigorous, coordinated regulation of its banking and financial systems by a single supervisor—that monetary union without banking union will not work.

The authors use the comparative behavior of real output growth and inflation behavior of members and nonmembers of the exchange rate mechanism (ERM) to analyze the importance of ERM membership on macroeconomic performance. An econometric procedure for identifying temporary and permanent shocks to output is proposed and executed. The results confirm that the ERM has acted as a vehicle for macropolicy coordination between members. The authors also investigate several issues relating to the hypothesis of global economic 'tri-polarity' between the United States, Germany, and Japan.