In June, the Supreme Court issued a landmark decision establishing that the Fair Housing Act prohibits the segregation of racial minorities and other historical targets of discrimination, even when that segregation is created by seemingly neutral policies like zoning laws. This legal milestone has arrived at an opportune time for advocates of civil rights and social justice. This is because, just months ago, new research effectively settled a long-running debate about the effect of neighborhoods on endemic poverty.

For nearly two decades, housing policymakers have been split over a fundamental question: Does moving to wealthier, less-segregated neighborhoods help families escape the cycle of poverty?

The debate started in the 1960s, when a lawsuit over racial segregation in Chicago's subsidized housing resulted in what is known today as the Gautreaux program: a dedicated effort to provide housing for low-income black families in affluent, and mostly white, suburbs. Social scientists who monitored Gautreaux participants found something startling. The children of families who moved to affluent areas appeared to be thriving. They were staying in school, finding jobs and going to college. By comparison, children in the city were still struggling.

In response, skeptics often cited a project from the 1990s, called Moving to Opportunity, in which the federal government helped families around the nation move to higher-income areas. The results were ambiguous, and many of the earlier benefits now seemed to be absent. But the project couldn't definitively settle the question of neighborhoods effects, because it had ignored racial integration in favor of economic integration — many participants moved to neighborhoods that were every bit as segregated as those they'd come from.

Last month, a new, comprehensive study by a pair of Harvard economists, Raj Chetty and Nathaniel Hendren, seems to have finally, firmly, resolved this debate.

The study examined over 2 million anonymized tax records, and analyzed changes experienced by families after moving between counties. It controlled for every conceivable confounding factor. The result is a stunning vindication of Gautreaux. Every single year a child spends in a "good" community correlates with higher future income, better college attendance rates and other positive outcomes. Likewise, every year in a "bad" neighborhood results in equal but opposite negative outcomes.

What's more, the study found that five factors determined whether a neighborhood was good — factors largely found in affluent suburban areas. They are the absence of segregated living patterns, less income inequality, better schools, low crime rates and a high share of two-parent households.

The resolution of this debate is especially significant for Minnesotans. Our region has a large industry dedicated to providing affordable housing to low-income families. In the Metropolitan Council, the region has a unique regional government with the legal authority to guide housing policy. In other words, Minnesotans have the tools to launch a powerful campaign against housing segregation, transforming lives and reducing poverty. In fact, in the 1960s and '70s, this is precisely what happened: the Met Council, emboldened by Gautreaux, enacted strong policies to integrate subsidized housing throughout the region.

But in more recent years, the Twin Cities' affordable-housing industry has mostly focused its work in the poorer areas of Minneapolis and St. Paul, allowing segregation to persist. And the Met Council has largely abandoned its strong effort to promote integrated neighborhoods. Today, its main program for creating a fairer mix of housing is voluntary, and dozens of communities ignore it.

The Harvard study provides a powerful impetus for reform. It proves the link between geography and poverty, and reaffirms that anyone who wants to fight the region's disturbing racial and economic disparities must also tackle its deeply rooted segregation. And it shows that time is of the essence. Every year children spend in segregated, low-opportunity neighborhoods, they fall further behind.

Where people live, it turns out, defines much of their lives. It's tempting to see this truth as depressing, an ugly element of determinism in a society that reveres self-reliance. But in reality, these new findings don't show how little we can change, but how much. Even endemic problems like poverty and segregation aren't as intractable as they seem, and we can slowly but surely unwind them with dedicated policymaking. One question remains: Will we?

Will Stancil, of Minneapolis, is a research fellow at the University of Minnesota's Institute on Metropolitan Opportunity.