Summersville is a census-designated place and unincorporated community in Green County, Kentucky, United States. As of the 2010 census it had a population of 568.It lies along Routes 61 and 323, 6 miles northwest of the city of Greensburg, the county seat of Green County. Its elevation is 804 feet. Although it is unincorporated, it has a post office, with the ZIP code of 42782. Annually in late July the residents host a festival named "Summersville Days".Summersville was incorporated in 1817.