Fairfield (1785) County was created out of Camden Circuit Court Distrct in 1785. Fairfield (1785) County, South Carolina and Lancaster (1785) County, South Carolina were divided into the following: Fairfield Circuit Court District (1800), Kershaw County in 1791, Lancaster District (1800).
Fairfield county was formed in 1785 as a part of Camden District. When Camden District was abolished in 1800, Fairfield County became known as Fairfield District. In 1868, it was again called Fairfield County. Its lines have remained unchanged to this day  except for a small portion ceded to Richland County in 1913. The town of Winnsboro, which was settled around 1755, is the county seat.
Fairfield County lies between the upcountry and the lowcountry areas of the state, and beginning in 1745 it was settled both by Scots-Irish immigrants from colonies to the north (primarily Pennsylvania and Virginia) and by English and French Huguenot planters from the lowcountry. In the colonial period this area was a center for the Regulator movement, which sought to bring law and order to the backcountry. During the Revolutionary War, Lord Cornwallis made his headquarters in Winnsboro from October 1780 to January 1781; the county was also invaded by General Sherman's troops during the Civil War.
See: Fairfield County, South Carolina for additional information, including maps.