It is in the 1930s that the "American Plan" of ad-supported radio flourishes, making it unlikely that proponents (and there were many) of the "European Plan" of a government-operated medium will prevail. The attractiveness of free, high-quality entertainment as an antidote to the Great Depression results in burgeoning audiences for the newly created radio networks, a key to wooing advertisers to the new mass medium. More advertisers beget more money for programming, and that draws stars from the legitimate stage, screen and vaudeville. Once dismissive of the box with wires, performers soon learn of the power of this very personal medium.
About 12 million U.S. homes have a radio in 1930. By 1940, that figure is 28.5 million, and car radios are becoming standard equipment.
Skyrocketing too are the fortunes of the major networks: NBC's Red and Blue, CBS and Mutual (plus numerous regional nets).
With radio personalities such as Jack Benny, Charles Correll and Freeman Gosden (Amos 'n' Andy), Eddie Cantor, Burns (George) and Allen (Gracie), and Major Bowes attracting larger and larger audiences, advertisers want more-precise listening figures. So, in 1936, A.C. Nielsen proposes its Audimeter, which attaches to a sampling of radio sets and measures audience size.