A new longitudinal study shows that regions in the United States with high levels of income inequality have suffered from consistently low levels of intergenerational mobility over the last century.

Michael Storper of the UCLA Luskin School of Public Affairs and Dylan Connor of Arizona State University co-authored the study, which was published by the Proceedings of the National Academy of Sciences. The study’s findings include:

  • Individuals growing up in urbanized and industrialized regions — such as in the Northeast, Midwest and West — experienced higher levels of intergenerational social mobility in the early 20th century, although this advantage declined over time.
  • People born in the South experienced consistently lower levels of social mobility throughout the 20th century.
  • Regions with large Black populations that face income inequality have suffered from consistently lower levels of social mobility.
  • An individual’s early childhood environment has gained increasing importance over time as a predictor of economic upward mobility in the country. In the early 20th century, for example, proximity to a city with employment opportunities in manufacturing was of greater importance than in today’s economy. Contemporary upward mobility is more likely to depend on educational success.

The authors analyzed location and income data from the U.S. Census for more than 1 million U.S.-born fathers and sons in 1920 and 1940, respectively, to measure regional social mobility in the early 20th century. They compared those findings with contemporary social mobility patterns derived from Internal Revenue Service data for 10 million children from the 1980–1982 birth cohorts and later observed from 2011–2012. Although the newer data capture the experiences of both males and females, the historical data only apply to males.

Why did the authors need to look back 100 years?

“The article’s central concern is intergenerational social mobility — meaning the probability that the children of one generation will or will not achieve a higher socioeconomic status than their parents,” said Storper, a professor of urban planning at the Luskin School. Although adult life may take place in a region different from one’s childhood, the region where a person starts life influences factors such as quality of schooling, social support structures and parental income.

“We have to know how the conditions of their childhood might have helped them be both geographically and socially mobile,” he said, “and whether geographical migrants are more socially mobile than stay-at-homes.”

Read the full news release.