Newton County is a county located in the U.S. state of Mississippi. As of the 2010 census, the population was 21,720. Its county seat is Decatur.
According to the U.S. Census Bureau, the county has a total area of 580 square miles (1,500 km), of which 578 square miles (1,500 km) is land and 1.5 square miles (3.9 km) (0.3%) is water.
As of the census of 2000, there were 21,838 people, 8,221 households, and 6,001 families residing in the county. The population density was 38 people per square mile (15/km²). There were 9,259 housing units at an average density of 16 per square mile (6/km²). The racial makeup of the county was 65.01% White, 30.37% Black or African American, 3.68% Native American, 0.18% Asian, 0.33% from other races, and 0.44% from two or more races. 0.91% of the population were Hispanic or Latino of any race.
There were 8,221 households out of which 33.50% had children under the age of 18 living with them, 53.00% were married couples living together, 16.00% had a female householder with no husband present, and 27.00% were non-families. 24.60% of all households were made up of individuals and 11.60% had someone living alone who was 65 years of age or older. The average household size was 2.57 and the average family size was 3.04.
In the county, the population was spread out with 26.20% under the age of 18, 11.20% from 18 to 24, 26.00% from 25 to 44, 21.70% from 45 to 64, and 14.90% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 92.40 males. For every 100 females age 18 and over, there were 88.70 males.
The median income for a household in the county was $28,735, and the median income for a family was $34,606. Males had a median income of $27,820 versus $20,757 for females. The per capita income for the county was $14,008. About 16.40% of families and 19.90% of the population were below the poverty line, including 26.30% of those under age 18 and 21.70% of those age 65 or over.