Business depression is characterized by low production, dull trade, hesitant investment, hoarding, low prices, liquidation, low interest rates, and unemployment. How long the depression lasts depends upon the degree of overproduction; the rejuvenation of business cannot begin until the oversupply is consumed and the necessary readjustments have been made in production. The depression may be broken by some fortuitous event, such as a presidential election, the signing of a treaty, the favorable turn of the balance of trade, and the like. The normal time required for the cycle of boom, panic, depression, and recovery is twenty years, with minor disturbances at the end of the first ten years. A certain periodicity in panics has been frequently pointed out, and such periodicity is exemplified by the American panics of 1819, 1837, 1847, and 1857; and of 1873, 1884, and 1893, and 1903, the more severe of which occurred in the years in heavy type.