The event often considered the start of the Great Depression in the U.S. is the stock market crash of October 1929. This powerful economic downturn resulted from a combination of factors, including excessive speculation, overproduction, and a lack of financial regulation. On October 29, known as Black Tuesday, millions of shares were sold, leading to a complete collapse of the financial system. This event triggered widespread bank failures, massive unemployment, and significant hardship, setting the stage for enduring economic challenges throughout the 1930s.