Comparative Perspectives on Income
From Pew:
The U.S. represents a significant exception to this general relationship between national income and the middle-income share. The median income in the U.S. – $53,000 – exceeded the median income in all countries but Luxembourg in 2010. As noted, however, the share middle class in the U.S. (59%) is less than in any of the selected countries from Western Europe.
The American experience reflects a marked difference in how income is distributed in the U.S. compared with many countries in Western Europe. More specifically, the U.S. has a relatively large upper-income tier, placed well apart from an also relatively large lower-income tier. This manifests not only as a smaller middle-income share but also as a higher level of income inequality. The gap between the earnings of households near the top of the income distribution and the earnings of those near the bottom is the widest in the U.S.