In 1951 the US Army made this film showing how an independent radio station operates. There was certainly a cold war propaganda motive for the US Army to produce this film, but today, when independent stations are a rarity, this film gives a detailed view of how a large market, independent radio station, WMCA New York, went about producing its programming and paying the bills in post war America.
You can watch it here:
https://youtu.be/ZN_J_bwrg4k73, Mark ~ AE2EA