As summer's close brings American students back into the classroom, school systems around the country, including the nation's largest in New York City, are taking stock of segregation in their districts and seeking ways to remedy it.

Last week, New York's School Diversity Advisory Group released new recommendations, which included substantial policy changes like reworking "gifted and talented" education to address the ways it concentrates white and Asian students in those programs and segregates them from their black and Latinx peers.

New York in 2019 and Nashville in the 1970s might seem far away from one another. But Nashville offers important lessons for the present. The most important: in many ways, desegregation works.

That lesson is backed by research conducted by economist Rucker Johnson and others, which showed desegregation in the 1970s and 1980s helped produce major increases in achievement levels in school and improvements in life outcomes for black students nationally, without harming outcomes for white children. Sociologist Amy Stuart Wells and colleagues have synthesized multiple studies showing favorable results for students' social learning as well.

So it was in Nashville. Countering old myths about 1970s- and 1980s-era desegregation's wholesale failure, Nashville did achieve statistical desegregation. Like many districts, Nashville spent a decade and a half after the 1954 Brown v. Board of Education decision resisting desegregation via gradualism, manipulated school zone lines and other tactics also familiar to school districts in the North.

Real desegregation

But starting in 1971, court-ordered desegregation, including buses transporting students to schools out of their neighborhoods, combined with a countywide district that included the city and its suburbs to yield desegregation. By 1980, when roughly a third of black students in the United States still attended schools that were more than 90% percent black, fewer than 5% did in Nashville. From 1983 into the late 1990s, the district had no schools that were more than 90% white.

And yet, Nashville's story also helps us to see failings and inequalities in the process of desegregation. Statistical desegregation did not guarantee equal concern about the education of all students or equality in the process of desegregation. In Nashville, as in many places across the country, white citizens and their allies in education and government made sure to protect what they perceived to be their interests even as their city desegregated. Again, and again, school systems like Nashville designed every aspect of how they desegregated to favor white students and communities over black students.

Nashville's desegregation plan closed several schools in black communities and opened new schools in segregated white suburbs far from the city center. As black school board member Barbara Mann put it, desegregation in practice communicated that black people lived in places not fit for schools.

Partly as a result, black students also spent more time and more years on the bus. This was an irritation for many families, but it was also a substantial barrier to student success. Many high school students, for example, could not join sports teams and other extracurricular activities because they had no way to get home afterward. With schools farther away from home, parents without cars (disproportionately likely to be black rather than white) struggled to support their children at events or parent-teacher conferences. Nashville did not ask white 5-, 6- and 7-year-olds to ride buses out of their neighborhoods, fearing their parents' opposition. But it made this demand of black children and families in thousands of cases. Many black families saw desegregation's benefits, but weighed them against these costs as well.

What these decisions illustrate is how the implementation of desegregation matters as much as its statistical outcomes. Most white parents in Nashville believed that local and federal government should bend in the direction of their felt needs, that white students' interests mattered more than the rights of black students. And their views were reinforced by the local white leadership in Nashville.

But it did not have to be that way.

Trying to get it right

Other Southern cities did desegregation differently. Louisville, still home to an extensive desegregation plan through local school district policy today, began busing for desegregation with students assigned to schools by alphabet rather than neighborhood, a randomness that delivered, at least in some respects, more equal outcomes (although black students still bore longer travel burdens on average).

Charlotte's citizens debated desegregation plans in many forms in the early 1970s, and questions of fairness — between poorer and richer white citizens as well as between white and black communities — were at the center of both public discussion and court supervision. Perhaps that experience helped undergird the city's elite white leadership in their public and unusually enduring endorsement of doing desegregation fairly.

Sadly, Nashville's resistance, rather than Charlotte or Louisville's commitment, was closer to the norm. Segregated schools long had been a clear manifestation of how government power could be organized in the interest of white people. Desegregation in the 1970s and 1980s continued the tradition, as black scholars like Derrick Bell pointed out then and as others have since.

Nashville's lead civil rights attorney Avon Williams Jr. recognized how unequal desegregation in Nashville was, and tried to address these inequalities on behalf of his and other black communities in the city. He wanted desegregation as an outcome and he wanted to achieve it via policies that treated black communities and children justly. He did not achieve that end.

With strong new research on desegregation's academic, social and civic benefits, advocates in New York and around the nation are imagining a new wave of desegregation. But will their effort seek not only statistical desegregation, but equality in the process of desegregation?

Neither in Nashville nor in most American school districts have we ever reaped the benefits of desegregation fairly and robustly implemented. Policymakers, parents, educators and other advocates of any new desegregation will have to decide whether we ever will.

Ansley T. Erickson, author of "Making the Unequal Metropolis: School Desegregation and Its Limits," is an associate professor of history and education at Teachers College, Columbia University and the co-editor of the forthcoming, "Educating Harlem: A Century of Schooling and Resistance in a Black Community."