Pulitzer Prize-winning journalist Wilkerson examines the migration of nearly 6 million African Americans from the South for the North and the West between World War I and the 1970s through the stories of three individuals: Ida Mae Gladney, who left rural Mississippi for Chicago in the 1930s; George Swanson Starling, who set out for Harlem in the 1940s; and Robert Joseph Pershing Foster, who became a Los Angeles physician after leaving Louisiana in the 1950s.