Income is inextricably linked to access to education in America and it has been for a century, according to a new study.

The study in the Proceedings of the National Academy of Sciences examines the link between education and income dating back to the early the 20th century.

The research draws upon a dozen nationally representative datasets on college enrollment and completion between 1908 and 1995 as well as tax data from more recent years. It is one of the first studies to examine this link over such an extended period of time.

The researchers found that income and educational inequality moved in lockstep with one another throughout the 20th century. The authors say previous studies of this topic, which haven’t examined data going so far back in time, did not reveal such a strong link.

Their paper details how inequality in college enrollment and completion rose in the 1930s and 1940s amid rising income inequality; was low for Americans born in the late 1950s and 1960s, when income inequality was low; and rose again for Americans born in the late 1980s, when income inequality peaked. This U-turn indicates the nation is experiencing levels of collegiate inequality not seen for generations, the authors write.

“Long story short, the findings reveal that longstanding worries about income inequality and its relationship to college opportunity are warranted,” says Brian Holzman of Rice University’s Houston Education Research Consortium, part of the Kinder Institute for Urban Research and School of Social Sciences, .

Read the full article about the relationship between educational and income inequality by Amy McCaig at Futurity.