County administrative offices are located at 207 North 1st Street, Westmoreland, KS 66559; phone: 785-457-3455.
Pottawatomie County was created by the Kansas Territorial Legislature out of Riley County in 1857. The area's earliest settlers were Catholic missionaries who established a mission at St. Marys in 1848 ahead of the Potawatomi Indians, who had been moved from district to district by the federal government. St. Marys was situated along the Oregon Trail, which passed through northeast Kansas and was used by emigrants in the mid-19th century as they made their way westward. In 1860, just prior to statehood, the county's population totaled 1529, and by 1870 the population had climbed to 7,848.