Integrated schools help to reduce racial achievement gaps. In fact, the racial achievement gap in K–12 education closed more rapidly during the peak years of school desegregation in the 1970s and 1980s than it has overall in the decades that followed—when many desegregation policies were dismantled. More recently, black and Latino students had smaller achievement gaps with white students on the 2007 and 2009 NAEP when they were less likely to be stuck in high-poverty school environments. The gap in SAT scores between black and white students continues to be larger in segregated districts, and one study showed that change from complete segregation to complete integration in a district could reduce as much as one quarter of the current SAT score disparity.
https://tcf.org/content/facts/the-benefits-of-socioeconomica...
Not only were they more successful in school, they were more successful in life as well. A 2011 study by the Berkeley public policy professor Rucker C. Johnson concludes that black youths who spent five years in desegregated schools have earned 25 percent more than those who never had that opportunity. Now in their 30s and 40s, they’re also healthier — the equivalent of being seven years younger.
http://www.nytimes.com/2012/05/20/opinion/sunday/integration...
Desegregation and Black Dropout Rates J, Guryan. 2001. has some good data on the decline in black dropout rates in districts with integration.