The stock market crash of 1929 was not the sole cause of the Great Depression, but it did act to accelerate the global economic collapse of which it was also a symptom. By 1933, nearly half of America's banks had failed, and unemployment was approaching 15 million people, or 30 percent of the workforce.
The reason we joined in world war one was due to the germans sinking merchant ships that had US citizens on them and they were also sinking some of our own ships. Due to that President Wilson involved us in the war.
