The B SideBy: Ben Yagoda From an acclaimed cultural critic, a narrative and social history of the Great American Songwriting era. Everybody knows and loves the American Songbook. But its a bit less widely understood that in about 1950, this stream of great songs more or less dried up. All of a sudden, what came over the radio wasnt Gershwin, Porter, and Berlin, but Come on a My House and How Much Is That Doggie in the Window? Elvis and rock and roll arrived a