As unionizing efforts have taken the U.S. by storm, we look at the history of the U.S. labor movement and how unions have acted as a bulwark against corporate power. Worker organizing at Starbucks, Kellogg’s and Amazon shows that unions help enforce health and safety measures and protect workers who speak out. “A working-class consciousness ebbs and flows,” says Nelson Lichtenstein, director of the Center for the Study of Work, Labor, and Democracy at the University of California, Santa Barbara. “A union is a way of capturing that consciousness and making it the law of the land.”