The country whose 1929 stock exchange crash became known as the October 1929 Wall Street Crash was the United States.
The crash centered on the New York Stock Exchange in New York City. Share prices had risen rapidly during the 1920s, and many investors bought stocks with borrowed money, a practice known as buying on margin.
Selling intensified in late October 1929, including the sessions commonly called Black Thursday, Black Monday, and Black Tuesday. The crash weakened confidence and contributed to the broader economic contraction that became the Great Depression.
The crash did not by itself create every cause of the Depression. Bank failures, reduced demand, international debt problems, trade restrictions, and monetary policy all mattered. The United States was the central market involved, while financial distress soon spread internationally.