Rural Free Delivery (RFD), since 1906 officially rural delivery, is a program of the United States Post Office Department to deliver mail directly to rural destinations. The program began in the late 19th century. Before that, people living in rural areas had to pick up mail themselves at sometimes distant post offices or pay private carriers for delivery.
Rural Free Delivery vehicle (from Popular Mechanics, September 1905)
The cast of the third and final season of Mayberry R.F.D., 1970. Back row, L-R: Ken Berry, Arlene Golonka, Buddy Foster. Front: George Lindsey (in hat), Jack Dodson, Alice Ghostley and Paul Hartman