At the time of incorporation in 1887, the City of Festus encompassed approximately 190 acres of land. This included the area south of the Burlington Northern Railroad tracks, north of Harrison Lane, and east of Sunset Park. It also included what was known as Derby City, W.A. Gamel Subdivision, McAllister Subdivision, Sherlock Subdivision, W.A. Adams Subdivision, and several pieces of farmland. In the 100 years since its incorporation, the city has grown to 2,300 acres, or about 3.6 square miles.