Franklin County was named for Benjamin Franklin: the exact reason remaining somewhat of a mystery. At one time much of the south end of the county was owned by LeRay de Chaumont, son of a French count, who greatly admired Franklin. In addition, a great number of the first settlers came from counties named Franklin in Vermont and Massachusetts.
Visit the U.S. Census Website for an array of demographic information.
U.S. Census information
Your link for the official Essex County Website.