Mound Bayou is a city in Bolivar County, Mississippi, United States. The population was 1,533 at the 2010 census, down from 2,102 at the 2000 census. It is notable for having been founded as an independent black community in 1887 by former slaves led by Isaiah Montgomery. By percentage, its 98.6 percent African-American majority population is one of the largest of any community in the United States.