The unemployment rate in the United States rose from about 6 percent in September 2008 to nearly 9 percent by April 2009 – it would peak at 10 percent in October – while inflation declined sharply. As the crisis crested, and with the federal funds rate at its effective lower bound, the FOMC turned to nontraditional policy approaches to support the recovery.
I propose to you the simple thought experiment: What would be, today, the US market if we would have had different currencies in California and Texas, Massachusetts and Wyoming? Would we call it an “achieved single market”? In that perspective, the single currency offers us all the economic benefits associated with an “achieved single market”.