Sumter County was created from Clarendon, Claremont and Salem Counties as Sumter District in 1798, named after General Thomas Sumter, and became effective in 1800. When the home of Sumter District's clerk of records burnt in 1801, the formative records of the three predecessor counties were also destroyed in the conflagration. So documentary evidence that the three counties were within St. Mark's Parish in Camden District derives from family genealogies and legislative records. On 19 December 1855, a legislative act was passed partitioning Sumter District by forming Clarendon District, with the same boundaries as defined for Clarendon County in 1785. When effectuated in 1857, a northeastern part of Sumter District was also separated in the partition. The Sumter District gained a form of self-rule and was renamed Sumter County under the 1868 Constitution. In 1898, a northwestern part of Sumter County was detached to form part of the first Lee County, but its formation was declared unconstitutional in 1899. In 1902, an even larger northern part of Sumter County was properly legally detached to form the major sections of the current Lee County, of which some acreage reverted in 1914. In 1921 southern Sumter County received a section from Clarendon County, of which some acreage reverted in 1922, creating the current boundaries of Sumter County.
Geography
According to the U.S. Census Bureau, the county has a total area of, of which is land and is water. It is drained by the Black River and its tributaries. Its western border is formed by the Wateree River. One of South Carolina's most famous areas are the High Hills of Santee comprising the western part of the county. The county is one of five that borders Lake Marion, also known as South Carolina's "Inland Sea."
As of the 2010 United States Census, there were 107,456 people, 40,398 households, and 28,311 families residing in the county. The population density was. There were 46,011 housing units at an average density of. The racial makeup of the county was 48.2% white, 46.9% black or African American, 1.1% Asian, 0.4% American Indian, 0.1% Pacific islander, 1.4% from other races, and 1.9% from two or more races. Those of Hispanic or Latino origin made up 3.3% of the population. In terms of ancestry, 7.2% were Subsaharan African, 6.9% were American, 6.1% were English, 5.9% were German, and 5.7% were Irish. Of the 40,398 households, 36.5% had children under the age of 18 living with them, 44.6% were married couples living together, 20.2% had a female householder with no husband present, 29.9% were non-families, and 25.8% of all households were made up of individuals. The average household size was 2.59 and the average family size was 3.11. The median age was 35.4 years. The median income for a household in the county was $39,137 and the median income for a family was $45,460. Males had a median income of $36,101 versus $28,421 for females. The per capita income for the county was $18,944. About 15.5% of families and 19.4% of the population were below the poverty line, including 29.1% of those under age 18 and 14.7% of those age 65 or over.
