Mound Bayou is a city in Bolivar County, Mississippi, United States. The population was 1,533 at the 2010 census, down from 2,102 in 2000. It was founded as an independent black community in 1887 by former slaves led by Isaiah Montgomery. Mound Bayou Historic District is listed on the National Register of Historic Places.

Bolivar County is a county located on the western border of the U.S. state of Mississippi. As of the 2020 census, the population was 30,985. Its county seats are Rosedale and Cleveland. The county is named in honor of Simón Bolívar, early 19th-century leader of the liberation of several South American territories from Spain.