The event that marked the beginning of the Great Depression in the United States was the stock market crash of October 1929, specifically the crash known as Black Tuesday, which occurred on October 29. This dramatic decline in stock prices led to widespread panic and loss of confidence in the financial markets. Many investors found themselves bankrupt, and banks rapidly failed, triggering a severe economic downturn. The Great Depression lasted through the 1930s, resulting in massive unemployment, business failures, and extensive economic hardship across the nation and beyond, fundamentally reshaping economic policies and government involvement in the economy.