South Main Street District is a historic district in Middletown, Ohio. It contains 76 contributing buildings, including single-dwelling, professional, and specialty store uses. The district was listed in the National Register of Historic Places in 1974. It includes the John B. Tytus House, which is a National Historic Landmark. Notes Historic districts on the National Register of Historic Places in Ohio Historic districts in Butler County, Ohio National Register of Historic Places in Butler County, Ohio