Growing family income gap in US linked to increasing gap in children’s completed education

Photo: Marie-Caroline Lanfranchi. Creative Commons.

The increase in the US family income gap—which rose from $100,000 between the top and bottom 20% of 14- to 16-year-olds in 1968 to $165,000 in 2009—is the biggest predictor yet found of the growing disparity in school completion between these groups, according to a new study. Over that period, the schooling disparity between the top 20% and bottom 20% of young people increased by half a year, and the income gap accounts for three-quarters of that difference, the study found.

The data, collected through the Panel Study of Income Dynamics, covered 6,072 young people.

The increasing income gap also accounted for half of the increasing disparity in college attendance and one-fifth of the increasing disparity in college graduation.

Contrary to the expectations of the research team, led by Professor Greg Duncan of the University of California, further analysis of the figures showed that the striking increase in single-parent families between the highest and lowest income groups accounted for virtually none of the growing school completion gap. At the start of the period, 42% of 14- to 16-year-olds in the low-income group lived with two biological parents; the figure dropped to 28% at the end of the period. The rate for the high-income group was 91% at both points.

The disparity in maternal education shrank in the first part of the period and then grew enough in the second part to become the second-strongest predictor of the growing school completion gap for their children.

The researchers were also surprised to find that a growing gap between the high- and low-income groups in mothers’ average age at the birth of a child correlated with an increase in the school completion gap among their children. For the low-income group, the average mother’s age at birth decreased from 27.9 to 24.7 years. For the high-income group, it increased from 27.4 to 28.7 years.

Income inequality has grown in nearly all industrialized countries in the past several decades. That this increase translates into divergent educational opportunities for US children suggests the need to redouble efforts to promote social mobility among young people.


Duncan GJ, Kalil A & Ziol-Guest KM (2017), Increasing inequality in parent incomes and children’s schooling, Demography