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.
Long Depression
The Long Depression was a worldwide price and economic recession, beginning in 1873 and running either through the spring of 1879, or 1896, depending on the metrics used. It was the most severe in Europe and the United States, which had been experiencing strong economic growth fueled by the Second Industrial Revolution in the decade following the American Civil War. The episode was labeled the "Great Depression" at the time, and it held that designation until the Great Depression of the 1930s. Though a period of general deflation and a general contraction, it did not have the severe economic retrogression of the Great Depression.