Fairfield, Sumner County, TennesseeFairfield is a census-designated place and unincorporated community in Sumner County, Tennessee, United States. As of the 2020 census, its population was 141, up from 131 at the 2010 census.HistoryIn 1808, a man called John Sarver settled the area. The community in the area grew around the terrain he had settled over time.