Dayton is a city and county seat in Rhea County, Tennessee, United States. As of the 2010 census, the city population was 7,191. The Dayton Urban Cluster, which includes developed areas adjacent to the city and extends south to Graysville, had 10,174 people in 2010.Dayton was the site of the Scopes Trial in 1925 dealing with the creation–evolution controversy.