Starting with "The Real McCoys", a 1957 ABC program, U.S. television had undergone a "rural revolution", a shift towards situation comedies featuring "naïve but noble 'rubes' from deep in the American heartland". CBS was the network most associated with the trend, with series such as "The Andy Griffith Show", "The Beverly Hillbillies", "Green Acres", "Mister Ed", "Lassie", "Petticoat Junction", and "Hee Haw". CBS aired so many of these rural-themed shows, many produced by Filmways, that it gained the nicknames the "Country Broadcasting System" and the "Hillbilly Network", a parody of their actual nickname, the Tiffany Network.