Sumter was incorporated in 1845 as Sumterville, and the name was shortened to Sumter in 1855. The city is named after General Thomas Sumter, who was known as the "Fighting Gamecock", who commanded troops in the American Revolutionary War and served in the United States Congress. Sumter started as a plantation settlement town, and grew over the years to be more industrialized. Today, industry in Sumter is mostly manufacturing, military, and medical related.

Sumter is served by a six-member city council, whose members are elected to represent a ward. A city manager is employed by council to run the day-to-day business of the city, and serves at the pleasure of council. Sumter has the distinction of being the first city in the United States to successfully implement this form of government, known as council-manager government. A mayor is elected at-large to a four year (renewable) term, and may vote with council only in the event of a tie vote.

Sumter is home to Shaw Air Force Base, headquarters of the 9th Air Force and the 20th Fighter Wing. Since World War II it has been one of the major sources of employment in the area. Shaw's fighter planes mainly consist of F-16 Fighting Falcons, which are versatile multi-role fighters. F-16's dispatched from Shaw were the primary fighters used in the Persian Gulf War. In response to the city's service, President George H. W. Bush came to Sumter to express his gratitude. Shaw is named after 2nd Lieutenant Robert Henderson Shaw, who was shot down and killed in action after a reconnaissance mission in World War I.

Sumter is home to the third largest school in the state (Sumter High School), whose current student population is 2,300. Sumter High is currently operated by the smallest school district in the state (Sumter District 17). The current building has been in use since 1983 and has undergone additions in 1987 and 2003; the 2003 additions opened to students in fall 2005 for the Class of 2006. Current feeder middle schools to Sumter High are Chestnut Oaks Middle, Alice Drive Middle and Bates Middle Schools. The SHS mascot is the Gamecock, a reference to the city and county's namesake, General Thomas Sumter. The school colors are royal blue and gold.

Sumter is home to the only public park in the United States with all eight species of swans (Swan Lake Iris Gardens). The City of Sumter hosts the "Iris Festival" which is centered around Swan Lake/Iris Gardens in May and is open to the public. Traditionally, the festival is held Memorial weekend. The park is also the host during the holiday season to the "Swan Lake Fantasy of Lights", a large light display open to the public.