Smithville was named for Humphrey and Nancy Smith who came west with their six sons and daughter from New York state in 1822 to find land and build a home. Settling along the Little Platte River, the Smith’s established Smith’s Mill, the first water-powered flour mill in Clay County. By the 1830s, a town site was laid out and Smith’s Mill became Smithville.
July 6, 1868, the town of Smithville was incorporated. Through the years, floods and fires changed the landscape of the city. In October 1979, the U.S. Army Corps of Engineers began impounding Smithville Lake, creating what is today a 7,200 acre lake with 175 miles of shoreline. Smithville Lake provides flood damage reduction, recreation opportunities, water supply and storage capabilities, as well as fish and wildlife management.