Copiah, from an Indian word meaning calling panther, was organized in 1823 as Mississippi's 18th county. It ranks seventh in land area. In the year of organization, Walter Leake served as governor and James Monroe as President of the United States.
The county is known as a tomato and cabbage producing area, and for many years was called the "Tomato Capital of the World."
Albert Gallatin Brown, the 14th governor of Mississippi, was elected from Copiah County, serving from 1844-48.
As of the census of 2000, there were 28,757 people, 10,142 households, and 7,494 families residing in the county. The population density was 37 people per square mile (14/km²). There were 11,101 housing units at an average density of 14 per square mile (6/km²). The racial makeup of the county was 47.80% White, 50.95% Black or African American, 0.07% Native American, 0.16% Asian, 0.01% Pacific Islander, 0.46% from other races, and 0.54% from two or more races. 1.15% of the population were Hispanic or Latino of any race.
There were 10,142 households out of which 34.40% had children under the age of 18 living with them, 48.70% were married couples living together, 20.10% had a female householder with no husband present, and 26.10% were non-families. 23.60% of all households were made up of individuals and 10.30% had someone living alone who was 65 years of age or older. The average household size was 2.71 and the average family size was 3.20.
In the county the population was spread out with 26.90% under the age of 18, 12.50% from 18 to 24, 26.80% from 25 to 44, 21.10% from 45 to 64, and 12.70% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 92.90 males. For every 100 females age 18 and over, there were 89.10 males.
The median income for a household in the county was $26,358, and the median income for a family was $31,079. Males had a median income of $28,763 versus $20,104 for females. The per capita income for the county was $12,408. About 22.00% of families and 25.10% of the population were below the poverty line, including 33.20% of those under age 18 and 21.20% of those age 65 or over.