In particular, they stressed the importance of risk sharing via fiscal and other means for a currency to work smoothly. And it is here, in my opinion, that the differences between the United States and the euro area are instructive as well.
In the United States, shocks are spread through the distribution of business profits and losses throughout the currency area, because company owners are often residents in other states. Another channel of private economic risk sharing is through saving and lending. Enterprises and households take out loans in different US states during an economic downturn to bridge a slump in earnings.