"The report by Chetty et al also suggests that geography and income percentiles interact in previously unknown ways. For instance, the percentile gradient for life expectancy at 40 years of age is steeper in Detroit, Michigan, than in San Francisco, California, or New York, New York, almost entirely because being in the bottom income percentile is worse in Detroit. However, this outcome in Detroit cannot be entirely related to income because this same income percentile in Detroit has more real purchasing power than in New York. (The adjustment for race and ethnicity may be an issue here.) Beyond Detroit, it is generally true that it is at the bottom of the income distribution, not at the top, where geography matters. It is as if the top income percentiles belong to one world of elite, wealthy US adults, whereas the bottom income percentiles each belong to separate worlds of poverty, each unhappy and unhealthy in its own way. The life expectancy at 40 years of age in the top income percentile of the United States is better than the mean in any other country for life expectancy at 40 years of age. However, not by a lot, and likely not better than the top percentile in Sweden or the Netherlands. In contrast, the life expectancy at 40 years of age in the bottom income percentile of the United States is located between the mean for Pakistan and Sudan for life expectancy at 40 years of age."That's from Angus Deaton's editorial in the latest issue of JAMA, referencing Chetty et al.'s The Association Between Income and Life Expectancy in the United States, 2001-2014.