Franklin County is a county located in the U.S. state of Kentucky. As of the 2020 census, the population was 51,541, making it the 2nd least populous capital county in the United States after Hughes County, South Dakota. Its county seat is Frankfort, the state capital. The county was formed in 1795 from parts of Woodford, Mercer and Shelby counties, and was named after the American inventor and statesman Benjamin Franklin.