Before the Civil War, the most important dividing line in the South was not between black and white, but between slave and free. Those categories track each other, but not perfectly, and what really mattered above all to most people when they had to make a choice was that slavery as an institution had to be preserved. But by the 19th century, there were enough people with some African ancestry who were living as respectable white people—people who owned slaves or supported slavery–that to insist on racial purity would actually disrupt the slaveholding South.
And this continued after the Civil War. With the rise of segregation in the Jim Crow era, separating the world by white and black required a renewed commitment to these absolute and hard-line understandings of race. But so many of the whites who were fighting for segregation had descended from people of color that even as laws became increasingly hard-line, there still was a tremendous reluctance to enforce them broadly.
One of your subjects, Stephen Wall, crossed from black to white to black to white again, in the early 20th century. How common was that crossing back and forth?
My sense is that this happened fairly often. There were many stories of people who, for example, were white at work and black at home. There were plenty of examples of people who moved away from their families to become white and for one reason or another decided to come home. Stephen Wall is interesting in part because at work he was always known as African-American, but eventually, at home everyone thought he was Irish.
How did that happen?
The family moved around a lot. For a while they were in Georgetown [the Washington, D.C. neighborhood], surrounded by other Irish families. Stephen Wall’s granddaughter remembered her mother telling stories that every time an African-American family moved anywhere nearby, Stephen Wall would pack the family up and find another place to live.
As you look at the United States now, would you say the color line is disappearing, or even has disappeared?
I think the idea that race is blood-borne and grounded in science still has a tremendous amount of power about how we think about ourselves. Even as we understand how much racial categories were really just a function of social pressures and political pressures and economic pressures, we still can easily think about race as a function of swabbing our cheek, looking at our DNA and seeing if we have some percentage of African DNA. I think that race has remained a potent dividing line and political tool, even in what we think of as a post-racial era. What my book really works to do is help us realize just how literally we are all related.