Median incomes stagnate as inequality increases Economists and other social scientists have long studied intergenerational income mobility, but consistent data linking adult incomes of children and their parents at similar ages over many generations have been unavailable, which thwarted attempts to study long-term trends. Chetty et al.'s study in this issue of Science (1) is therefore a tour de force for producing historically comparable estimates of absolute income mobility—the fraction of individuals in a birth cohort who earn, at age 30, more than their parents did at roughly the same age—over the post–World War II period. Their striking conclusion is that there has been a large decline in the rate of upward mobility across successive U.S. birth cohorts, from 92% of children born in 1940 earning more than their parents to only half of children born in 1984. Although Chetty et al. find that the slowdown in Gross Domestic Product growth has played a role, they conclude that faster economic growth is insufficient to restore mobility to its immediate postwar level in light of increased income inequality—a critical insight for policy and research.

中文翻译：

---

记录美国经济流动性下降

随着不平等的加剧，收入中位数停滞不前 经济学家和其他社会科学家长期以来一直在研究代际收入流动性，但一直没有将多代相似年龄的儿童及其父母的成人收入联系起来的一致数据，这阻碍了研究长期趋势的尝试。因此，Chetty 等人在本期《科学》(1) 中的研究是对绝对收入流动性进行历史可比估计的绝技——出生队列中 30 岁时收入超过父母的个人比例在大致相同的年龄——在二战后时期。他们惊人的结论是，美国连续出生队列的向上流动率大幅下降，从 1940 年出生的儿童中 92% 的收入超过其父母，到 1984 年出生的儿童中只有一半。发现国内生产总值增长放缓起了一定作用，他们得出结论，鉴于收入不平等加剧，较快的经济增长不足以将流动性恢复到战后的水平——这是政策和研究的重要见解。