What does the "K" stand for in news channels?

Question

like KTSF or KNBR...

Answer 1

Back when radio was first starting out.  There was two competitors, Mr Westshire and Mr Kaiser.  They decided to split the United States.  Mr Westshire got east of the Mississippi river and Mr Kaiser got west of the Mississippi river.

Answer 2

It is part of the traditional FCC station identifier. All broadcast transmitters west of the Missippi river start with the letter K and those east of the Missippi start with W.

  Incidently, AM radio stations with Three letter callsigns are clear channel stations, which means that they are license to have exclusive use of their assigned frequency, WSM in Nashville and WLS in Chicago are clear channel stations.