Beaver Cleaver's family lived in "Mayfield" in an unnamed state. The Anderson family lived in "Springfield" in an unnamed state. Sheriff Andy Taylor lived in a real state -- North Carolina -- but in an unreal town, Mayberry.But Dick Van Dyke Show creator Carl Reiner placed his fictional family, the Petries, in a house on a real street in a real city; in fact, on a street on which Reiner had lived: Bonnie Meadow Road in New Rochelle, New York. (The Petries' address of 148, however, does not exist in real life).
Here's an aerial view of the neighborhood today. According to tax rolls I found online, the houses shown here are the same ones that existed at the time of the show; most were built in 1954. We learn, in "Your Home Sweet Home is My Home", that Rob and Laura bought their house when it was new, for $27,990. Adjusted for today's dollars, that would be about $234,000 -- yet the tax rolls show the values of the homes on Bonnie Meadow Road today to be a half million dollars and up. It seems the Petries made a good buy.