The event that marked the beginning of the Great Depression in the U.S. was the stock market crash of October 29, 1929, commonly referred to as Black Tuesday. On this day, stock prices plummeted, resulting in panic selling and massive financial losses. The crash had a domino effect, leading to widespread bank failures, bankruptcies, and a significant decline in consumer spending and investment. This economic downturn triggered a prolonged period of economic hardship, unemployment, and social suffering that defined the 1930s, profoundly affecting American society and the global economy.