When officials of the U.S. Department of Justice came in 1961 to Panola County in the Mississippi delta, they found a closed society in which race relations had not altered significantly since Reconstruction. Much has changed, however, in Mississippi in the past three decades, as Frederick Wirt demonstrates in " We Ain't What We Was ," a remarkable look inside the New South. In this follow-up to his highly praised 1970 study of Panola County, The...