When William Henry Hunt married Ida Alexander Gibbs in the spring of 1904, their wedding was a dazzling Washington social event that joined an Oberlin-educated diplomat's daughter and a Wall Street veteran who could trace his lineage to Jamestown. Their union took place in a world of refinement and privilege, but both William and Ida had mixed-race backgrounds, and their country therefore placed severe restrictions on their lives because at that time, -one drop of colored blood- classified anyone as a Negro. This -stain- of melanin pushed the couple's achievements to the margins of...