Sumter County, South Carolina: History
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. As a result, documentary evidence that the three counties were within St. Mark's Parish (formed in 1757 from Prince Frederick's Parish, Craven County) in Camden District (formed 1769) derives from family genealogies and legislative records.
On December 19, 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 (formerly in Salem County) was also separated in the partition (the area east of a line drawn from the northernmost point of old Clarendon County continued north-northeasterly to a point on the boundary line with Darlington District (Sumter County's northeastern cornerpoint abutting Florence County since 1888).
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 (more or less the remaining part of former Salem 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.