For the reviewer who gave the book one star: how are you defining race? How are you defining "segregation?" To say that blacks received harsher treatment in the South since the Civil War has some history behind it, but that ignores the treatment of blacks in inner cities (urban segregation) of the North. In short, when you generalize about race, you miss the point that race is and always has been a complex, shifting negotiation of power, privilege, and exclusion that affects people no matter where they live. As for the civil war, the presence of nearly-white "fancy girls" helped drive the abolitionist movement forward--especially in the "mock" slave auctions performed by Henry Ward Beecher (Harriet Beecher Stowe's brother) in his famous Plymouth Church. Many abolitionists were prejudicial about skin tone and held tight to a European beauty aesthetic.
In short, when Northern whites pictured "one of their own" in bondage, the institution of slavery became all the more hideous. For more on this melodramatic "substitution" of victimhood, see Saidiya Hartman's _Scenes of Subjection_. It was a process similar to, and I can't believe I'm referencing this movie (or this actor), Matthew McConaughey's closing statement at the end of _A Time to Kill_, in which he asked the white jury members to picture that the little black girl attacked by those white men had, in fact, been white. Empathy is a powerful thing, and most powerful when we can imagine ourselves in the position of another.
Please don't listen to negative reviews of this book based on ahistorical and misinformed thoughts on "race." When we look at race only in terms of skin color we miss out on the history of a term that has structured American political, economic, and social life throughout history. This book answers the call for more complicated narratives about history. History, indeed, is always written by someone with an agenda, and the only way to get close to some sort of accuracy is by inviting various, sometimes conflicting approaches to what is never an easy subject.