Whenever the world economy is strengthened, the U.S. benefits. However, this should not lead us to understate or neglect the significant changes in trade flows, current account balances, and exchange rates that might be part of the transition to an increased international role of the euro, and the importance of careful management of this transition.
It is only fair, however, to warn my euro friends that having a preeminent international currency has its pluses and minuses — it is not an unmitigated free ride, as some of the discussion has suggested. There is a burden that accompanies having an international currency.