In 1959, Dallas journalist John Howard Griffin used drugs and sunlamps to darken his skin and then traveled through Louisiana, Mississippi, Alabama, and Georgia posing as a black man and keeping a diary of his experiences. He found it to be “the story of the persecuted, the defrauded, the feared and the detested.” When he applied for work at a plant in Mobile, the foreman told him, “No, you couldn’t get anything like that here.” His voice was not unkind. It was the dead voice one often hears. Determined to see if I could break in somehow, I said: ‘But...