Duncan is a town in Bolivar County, Mississippi, United States. The population was 423 at the 2010 census, down from 578 in 2000.
Duncan is named for an early "leading citizen."
According to the United States Census Bureau, the town has a total area of 0.9 square miles (2.3 km2), all land.
As of the census of 2000, there were 578 people, 177 households, and 124 families residing in the town. The population density was 620.7 people per square mile (240.0/km2). There were 186 housing units at an average density of 199.7 per square mile (77.2/km2). The racial makeup of the town was 19.55% White, 77.51% African American, 2.25% from other races, and 0.69% from two or more races. Hispanic or Latino of any race were 3.11% of the population.
There were 177 households, out of which 42.4% had children under the age of 18 living with them, 36.2% were married couples living together, 26.0% had a female householder with no husband present, and 29.4% were non-families. 24.3% of all households were made up of individuals, and 11.3% had someone living alone who was 65 years of age or older. The average household size was 2.95 and the average family size was 3.47.