Dayton is a city in Rhea County, Tennessee, United States. The population was 6,180 at the 2000 census. The Dayton, TN, Urban Cluster, which includes developed areas adjacent to the city and extends south to Graysville, Tennessee, had 9,050 people in 2000. Dayton is the county seat of Rhea County. Dayton was the site of the Scopes Trial in 1925. Bishop Joseph Aloysius Durick was born in Dayton on Oct. 13, 1914.