High Quality Content by WIKIPEDIA articles! High Quality Content by WIKIPEDIA articles! Greenfield Township is one of the thirteen townships of Fairfield County, Ohio, United States. The 2000 census found 4,944 people in the township, 4,465 of whom lived in the unincorporated portions of the township. Parts of two municipalities are located in Greenfield Township: the city of Lancaster, the county seat of Fairfield County, in the southeast; and the village of Carroll in the northwest. Statewide, other Greenfield Townships are located in Gallia and Huron Counties.