In which year did the U. S. stock market crash signaling the onset of the Great Depression?

1929
The Great Depression was the worst economic downturn in US history. It began in 1929 and did not abate until the end of the 1930s. The stock market crash of October 1929 signaled the beginning of the Great Depression. By 1933, unemployment was at 25 percent and more than 5,000 banks had gone out of business.