On January 12, 1926, radio audiences heard the first exchanges of wit and wisdom between "Sam 'n' Henry"--the verbal jousters who would evolve into Amos 'n' Andy and whose broadcasts launched the radio sitcom. Here is a detailed look at 20 of the most popular such sitcoms that aired between the mid-1920s and early 1950s, the three-decade heyday of radio. Each series is discussed from an artistic standpoint, with attention to the program's...