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.
Financial contagion
One of the biggest worldwide crises was the stock market crash on Wall Street in October 1929. The failure from 1929–33 was foreshadowed by collapses in commodity prices in multiple emerging nations. The stock market boom in New York by 1928 choked off U.S. capital flows to central Europe and Latin America and precipitated currency crises in a number of countries (Australia, Argentina, Uruguay, and Brazil) and early in 1929. The Wall Street crash caused stock market scares globally. This is known as the Great Depression. The U.S. crisis in 1929 turned into the Great Depression by 1930 and 1931 because the Federal Reserve was unsuccessful at relieving multiple banking panics. The resultant collapse in prices and output worldwide forced sovereign borrowers to cut back on servicing their debts and then to default, precipitating a collapse of foreign lending in 1931.