The industrialization of the United States in the late 1800s led to rapid growth in key industries like steel, oil, and railroads. Large corporations and industrialists like Carnegie and Rockefeller exploited workers and natural resources to build vast fortunes. While industrialization increased productivity and consumer goods, it also led to long work days for low pay in unsafe conditions. Unions like the Knights of Labor and AFL organized to advocate for workers' rights, but faced violent opposition from businesses and government. Overall, rapid industrialization transformed the US economy but also exacerbated tensions between big business and labor.