In 1906, speaking from a homemade soapbox near Times Square, 16-year-old Elizabeth Gurley Flynn stopped traffic on a Saturday night. Broadway producer David Belasco became so impressed he wanted to put her on stage. But she told him, "I'm in the labor movement and I speak my own piece". And for more than 50 years this fiery American radical truly did speak her own piece, crossing and recrossing the United States, crusading for her brand of humane socialism. As the only woman leader of the Industrial Workers of the World she organized immigrant factory workers in the East, iron ore miners on...