[3] Sumter County comprises the Sumter, SC Metropolitan Statistical Area, which is also included in the Columbia-Sumter-Orangeburg, SC Combined Statistical Area.

On September 17, 2024, the National Park Service announced that the City of Sumter and Sumter County were jointly named a World War II Heritage City.

[6] So 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.

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".

[18] 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.

[25] As of April 2024, some of the largest employers in the county include Becton Dickinson, Central Carolina Technical College, the city of Sumter, Continental AG, the United States Department of Defense, Eaton Corporation, SKF, JCPenney, Pilgrim's Pride, Prisma Health, Speedway, and Walmart.

[27] Additionally, the University of South Carolina Sumter is located in the county.