The labor movement espoused social equality and honest labor through the formation of labor unions. Although groups such as the Knights of Labor and the American Federation of Labor, both of which represented skilled laborers, began to figure prominently in industry in the late 1800s, labor unions that represented unskilled workers did not gain influence until the early 1900s. By the 1930s, labor unions were becoming more accepted, thanks in part to the National Labor Relations Act, which gave workers the right to establish unions without interference from their employers. Crisply written and illustrated with compelling photographs, The Labor Movement, Revised Edition is a thorough look at the movement that has had a profound effect on how industry operates in the United States.