What event is commonly identified as the start of the Panic of 1873 in the United States?

The failure of Jay Cooke and Company is commonly identified as the start of the Panic of 1873 in the United States.

On 18 September 1873, the major investment bank suspended payments after it could not sell enough Northern Pacific Railway bonds. The railroad boom had encouraged heavy borrowing and speculation, while investors became increasingly unwilling to finance new projects.

The failure helped trigger a banking panic and a long economic depression. The New York Stock Exchange closed temporarily, and railroad companies, banks, and businesses faced falling prices and reduced credit. The crisis was part of a wider international downturn that also involved financial stress in Europe.

The Panic of 1873 is sometimes called the Long Depression, although economic historians debate the duration and severity of that label. It was not caused by one company alone; overbuilding, debt, speculation, and monetary disputes all mattered.