Moreover, wage flexibility meant that substantially slower wage growth in the states that lost industries helped to attract and retain other industries. And the US fiscal system collects roughly two-thirds of all taxes at the national level, which implies an automatic and substantial net fiscal transfer to states with temporarily falling incomes.
那么，为何美国50个州各不相同，却仍然可以实行单一货币？有三个关键的经济因素——这些在欧洲都不存在——允许多元化的美国实行单一货币：劳动力的流动性、工资的弹性，以及中央财政体系