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. Mound Bayou has a 96.8% African-American majority population in 2020, one of the largest of any community in the United States.