The event in 1929 that marked a significant economic downturn in the United States was the stock market crash that occurred in October, commonly referred to as Black Tuesday. This event signaled the beginning of the Great Depression, a decade-long economic crisis characterized by widespread unemployment, bank failures, and a significant drop in consumer spending. The crash was a result of speculative investments, overproduction, and an unstable banking system. Its aftermath had dire consequences not only for the United States but also for the global economy, leading to extended economic hardship and influencing many governmental reforms in subsequent years.