Fayette County was created by act of the Indiana General Assembly in Dec. 1818 from portions of Wayne and Franklin counties and unincorporated (“New Purchase”) territory in the northern portion of the county. It was named for the Marquis de la Fayette, a French hero of the Revolutionary War.
Connersville, then a small village of less than a hundred inhabitants, was designated the county seat. The county was divided into five townships (Harrison, Connersville, Jennings, Columbia and Brownsville) in February 1819, “Connersville” containing the namesake town. In 1821, the organization of Waterloo Township subsumed the portion of Brownsville Township remaining in Fayette County, along with a portion of Harrison Township west of the Whitewater River.
The far eastern part of Fayette lying between the Treaty of Greenville treaty line of 1795 and the present eastern boundary line of Waterloo and Jennings townships remained a part of Fayette County until it was split off into the newly created Union County in 1821. In 1826, a small part in the southeastern portion of Jackson Township not included in the limits of the county in 1818, being left a part of Franklin County was attached to Fayette County. In 1841, Connersville became the first, and remains the only, incorporated town (chartered as a city in 1869) in the county.