Major roads

• Mississippi Highway 12
• Mississippi Highway 14
• Mississippi Highway 19
• Mississippi Highway 35
• Mississippi Highway 43
• Natchez Trace Parkway

Adjacent counties

• Montgomery County (north)
• Choctaw County (northeast)
• Winston County (east)
• Leake County (south)
• Madison County (southwest)
• Holmes County (west)
• Carroll County (northwest)

National protected area

• Natchez Trace Parkway (part)

2020 census

As of the 2020 United States Census, there were 17,889 people, 6,941 households, and 4,735 families residing in the county.

2010 census

As of the 2010 United States Census, there were 19,564 people living in the county, down from its peak in 1940. 56.2% were White, 42.0% Black or African American, 0.3% Asian, 0.2% Native American, 0.7% of some other race and 0.6% of two or more races. 1.7% were Hispanic or Latino (of any race).

2000 census

As of the census^[12] of 2000, there were 19,661 people, 7,567 households, and 5,380 families living in the county. The population density was 27 people per square mile (10 people/km²). There were 8,639 housing units at an average density of 12 units per square mile (4.6 units/km²). The racial makeup of the county was 58.34% White, 40.00% Black or African American, 0.17% Native American, 0.27% Asian, 0.65% from other races, and 0.57% from two or more races. 1.42% of the population were Hispanic or Latino of any race.

There were 7,567 households, out of which 32.10% had children under the age of 18 living with them, 50.30% were married couples living together, 16.70% had a female householder with no husband present, and 28.90% were non-families. 26.40% of all households were made up of individuals, and 14.50% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the average family size was 3.07.

In the county, the population was spread out, with 25.90% under the age of 18, 9.20% from 18 to 24, 25.20% from 25 to 44, 22.40% from 45 to 64, and 17.30% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 91.50 males. For every 100 females age 18 and over, there were 86.70 males.

The median income for a household in the county was $24,794, and the median income for a family was $30,796. Males had a median income of $26,180 versus $17,394 for females. The per capita income for the county was $13,782. About 18.30% of families and 21.80% of the population were below the poverty line, including 28.60% of those under age 18 and 21.40% of those age 65 or over.

Cities

• Kosciusko (county seat)

Towns

• Ethel
• McCool
• Sallis

Unincorporated communities

• Hesterville
• McAdams
• Possumneck
• Williamsville
• Zama

Ghost towns

• Sand Hill
• Valena