Isabel Wall (l) and her siblings in 1909, the year she was expelled from school for being black.

Many persons of African American heritage but white appearance crossed the color line at times when racial classification had very real and harsh implications. Legal scholar Daniel Sharfstein chronicles the lives of three such families, the Gibsons, the Spencers and the Walls, who made the transition from black to white during the eighteenth and nineteenth centuries. To learn more about the book, Invisible Line, and to read an interview with the author, click here.