Jefferson was settled in 1812, and the borough was incorporated in 1866. The town was named after President Thomas Jefferson; however, in 1866, when the town was incorporated, the name Jefferson was already taken from a town in Greene County near Pittsburgh. So, the residents of the York County Jefferson chose “Codorus”, as its postal address, since it is in Codorus Township. The annual Jefferson Carnival benefits the Jefferson Volunteer Fire Company, Jefferson Sportsmen’s Association, and Jefferson Baseball Association. Students in Jefferson are served by the Spring Grove Area School District.