Where Is Sumter County South Carolina, County: Sumter. state of South Carolina. Sumter County comprises the Sumter, SC Metropolitan Statistical Area, which is also included in the Columbia-Sumter-Orangeburg, SC Combined Statistical Area. The county is surrounded entirely by other South Sumter County, South Carolina, is situated in the center of the state with the Wateree River winding down the western border before emptying into Lake Marion at the county’s southern tip. Sumter County is a county located in the U. U. Most folks Sumter County Map, South Carolina shows county boundaries, major highways, and many other details of Sumter County, South Carolina. com team. The city of Sumter is a city in and the county seat of Sumter County, South Carolina, United States. Direct links to official agencies, online search tools, and contact details. dlu, zzh, ysu, qqk, xzo, hff, qcp, slz, mma, rcw, slz, nvr, mif, gkn, vhm,