The beginning of the Great Depression in the United States is often marked by the Stock Market Crash of October 1929. This event caused widespread financial devastation and a loss of confidence in the economy. The crash led to bank failures, drastic declines in consumer spending, and massive unemployment. It marked the onset of a decade-long economic downturn that severely impacted American society and the global economy, prompting the government to implement significant reforms and programs to address the crisis.