Deflation
Deflation occurred periodically in the U.S. during the 19th century (the most important exception was during the Civil War). This deflation was at times caused by technological progress that created significant economic growth, but at other times it was triggered by financial crises — notably the Panic of 1837 which caused deflation through 1844, and the Panic of 1873 which triggered the Long Depression that lasted until 1879. These deflationary periods preceded the establishment of the U.S. Federal Reserve System and its active management of monetary matters. Episodes of deflation have been rare and brief since the Federal Reserve was created (a notable exception being the Great Depression) while U.S. economic progress has been unprecedented.
Economic collapse
While arguably not a true economic collapse, the decade of the 1930s witnessed the most severe worldwide economic contraction since the start of the Industrial Revolution. In the US, the Depression began in the summer of 1929, soon followed by the stock market crash of October 1929. American stock prices continued to decline in fits and starts until they hit bottom in July 1932. In the first quarter of 1933, the banking system broke down: asset prices had collapsed, bank lending had largely ceased, a quarter of the American work force was unemployed, and real GDP per capita in 1933 was 29% below its 1929 value. The ensuing rapid recovery was interrupted by a major recession in 1937-38. The USA fully recovered by 1941, the eve of its entry in World War II, which gave rise to a boom as dramatic as the Depression that preceded it.