The country whose 1929 stock-market crash is associated with the phrase ‘Wall Street Crash’ is the United States.
The term refers to the collapse centered on the New York Stock Exchange in New York City. The most famous sessions occurred in late October 1929, including Black Thursday on 24 October and Black Tuesday on 29 October. American share prices had risen dramatically during the 1920s before speculation and margin borrowing became widespread.
The crash destroyed market wealth and undermined confidence, but it was one part of the wider Great Depression. The United States experienced bank failures, industrial contraction, unemployment, deflation, and reduced international trade. Economic problems then spread across much of the world.
The phrase can be confused with the London Stock Exchange’s 1720 South Sea Bubble or the 1873 Vienna collapse. Those were different financial crises; “Wall Street Crash” conventionally identifies the United States event of 1929.