620 has been the home of KTAR and its predecessors KFAD and KREP since late 1928. It is the longest-used frequency in Arizona.

The Arizona Republic bought KFAD AM 930 from the McArthur Brothers Mercantile Co. in early 1929 and changed the calls to KREP. For reasons unknown they changed the call letters to KTAR a few months later. KTAR stood for "Keep Taking the Arizona Republic." The paper owned the station until Eugene C. Pulliam purchased the company in 1946 and sold the radio station.

KTAR was the home of the NBC Radio Network from 1930 to 1982. It has been affiliated with ABC ever since.

KTAR has had a news/talk format since 1973, when it debuted "Action News," a slogan also used by its then-sister station KTAR-TV Channel 12 (now KPNX-TV). The station is heavy with sports programming and is the flagship station for the Phoenix Suns and Arizona Diamondbacks. It also has carried the Phoenix (now Arizona) Cardinals and Arizona State University sports in the past.

The 620 transmitter is located at 38th St. & Thomas Rd. in the parking lot for Desert Vista (formerly Tower Plaza) mall. The mall was literally built around the towers in 1958 since the transmitter and its 2 towers have been there since 1941 when there was nothing but farms in the area.