Why Do American Broadcasting Radio Stations Use the Call Letters K and W and What Do They Mean?

During the 1920s, while radio was in its infancy, the FCC assigned the letter K to all stations west of the Mississippi and the letter W to all those east of the river.

Exceptions were made for stations with established call signs, like KDKA in Pittsburgh, and those affiliated with a network.

The other three letters are the broadcaster’s choice.