The United States is one of a handful of advanced countries with a growing workforce, owing to its relative openness to immigration. But this may change as the source countries become richer and undergo rapid declines in birth rates.
与此同时，大多数主要经济体的劳动力也已经或即将达到顶峰。德国、日本和俄罗斯的劳动力数量已经开始下降。美国是少数劳动力仍在增长的国家之一，这要归功于其相对开放的移民政策。但随着移民母国逐渐发达、出生率逐渐下降，美国的情况也会很快有所改变。因此，许多发达国家将不得不考虑如何让其国民高效地工作到70岁。