The rise of the modern labor movement in the United States was driven by industrialization, poor working conditions, low wages, and the exploitation of labor, particularly during the late 19th and early 20th centuries. Workers organized into unions to push for better rights and protections, driven by events like the Great Railroad Strike of 1877, the Haymarket Affair, and the establishment of the American Federation of Labor in 1886. Economic hardships during the Great Depression intensified these efforts, culminating in significant legislation, including the National Labor Relations Act of 1935, which solidified workers' rights to unionize.