By 1860, the year before the Civil War, 12 cities in Missouri had populations of approximately 2,500 or more. Harrisonville ranked 37th, with a population of 675. In 1863 the town was depopulated, as the United States forces pushed the people out in an effort to reduce any local support for insurgent guerrilla activity in the area. Most of the buildings were burned, the jail among them. Fort Harrisonville was a Union stronghold for a brief period in 1863 and provided protection for loyal Union families.