Mississippi Highway 178 (MS 178), or simply "Old 78", is a 119.1-mile-long (191.7 km) east-west state highway across the northern portion of the state of Mississippi. It is the former alignment of U.S. Route 78 (US 78), used from the 1940s until the 1990s. With the exception of a break at the Tennessee-Tombigbee Waterway in Fulton, MS 178 is a complete route from Memphis, Tennessee, to the Alabama state line.

Hickory Flat is a town in Benton County, Mississippi, United States. The population was 601 at the 2010 census.