- Sumter is a city located in South Carolina, United States. It is the county seat of Sumter County and is known for its rich history and diverse community. The city has a population of approximately 40,000 people, making it the eighth-largest city in the state. Sumter offers a variety of cultural and recreational amenities, including museums, parks, and annual events. The economy is largely based on industries such as manufacturing, healthcare, and education. Sumter is also home to Shaw Air Force Base, which contributes to the local economy and provides employment opportunities.