 KAAM is a Class B station operating on the clear-channel frequency of 770 AM.The KAAM format began when the city of Dallas sold WRR, its AM station on 1310 kHz, to Bonneville Broadcasting in January 1978.In 1921, WRR (now known as KTCK) had been the first licensed radio station west of the Mississippi River, and only the second in the U.S. Because the city was going to retain the WRR call letters for its classical music FM station, Bonneville changed the 1310 call letters of the AM station to KAAM and added an FM station on 92.5 with the callsign KAFM.