The rise of corporations and monopolies in late 19th-century America transformed the economic landscape. Rapid industrialization, technological advancements, and laissez-faire policies fueled the growth of powerful companies that dominated key industries like oil, steel, and railroads. This era saw the emergence of influential industrialists like Rockefeller and Carnegie, who built vast business empires through vertical and horizontal integration. Their practices led to increased efficiency and productivity but also raised concerns about worker exploitation, wealth concentration, and anti-competitive behavior, sparking government regulation and social reform movements.