The civil rights movement that loomed over the 1950s and 1960s was the tip of an iceberg, the legal and political remnant of a broad, raucous, deeply American movement for social justice that flourished from the 1920s through the 1940s. This contentious mix of home-grown radicals, labor activists, newspaper editors, black workers, and intellectuals employed every strategy imaginable to take Dixie down, from a ludicrous attempt to organize black workers...