“In 1900, industrial workers toiled 10 hours a day, 6 days a week and earning an average of $375 dollars a year. ...[W]orking conditions were typically unsanitary, unsafe, and often fatal, and there were few protections—whether from unions (...a meager 5 percent of industrial workers), employers, or government. ...[S]tate and federal governments frequently trotted out their armed militias to help suppress striking laborers. ...[W]hites lived an average of only 47 years, blacks a mere 33.”