A Grande Depressão

"The contraction from 1929 to 1933 was by far the most severe business-cycle contraction during the near-century of U.S. history we cover, and it may well have been the most severe in the whole of U.S. history... U.S. net national product in constant prices fell my more than one-third... From the cyclical peak in August 1929 to the cyclical trough in March 1933, the stock of money fell by over a third...At the trough of the depression one person was unemployed for every three employed."
Milton Friedman e Anna Jacobson Schwartz, A Monetary History of the United States, 1867-1960, Princeton University Press: Princeton 1963, p. 301