In the first half of the twentieth century, four million African Americans left the Jim Crow South to create new lives for themselves. They moved to cities like Detroit, Baltimore, and Chicago in what came to be known as “the Great Migration.” And indeed, they did improve their economic standing, with some families doubling their earnings. But opportunities to move up the ladder would dwindle for the generations that followed. In a paper in the American Economic Review, Ellora Derenoncourt shows that the way northern cities responded to the migration dampened the earnings potential for African Americans living in those locations today.  She says the findings offer insights into how some policies that encourage families to move to opportunity, such as voucher programs, ignore more fundamental questions about the elements that make neighborhoods thrive. Derenoncourt spoke with Chris Fleisher about her research, the mechanisms that reduced earnings potential for Black residents in some northern cities, and the implications for programs aimed at moving low-income and minority families to opportunity.