Grantville is a city in Coweta County, Georgia, United States. The 2020 census shows a population of 3,103. Grantville is located along the s…Grantville is a city in Coweta County, Georgia, United States. The 2020 census shows a population of 3,103. Grantville is located along the southern border of Coweta County. U.S. Route 29 runs through the city, passing south of the center, while Interstate 85 passes through the eastern part of the city, crossing US 29 at Exit 35. I-85 leads northeast 46 miles to Atlanta and southwest 114 miles to Montgomery, Alabama, while US 29, a more local road, leads north 12 miles to Newnan, the Coweta County seat, and southwest 20 miles to LaGrange.