WFAA (AM), which would eventually serve as the sister radio station to WFAA television, first signed on the air on June 26, 1922. The station had long participated in a time-sharing arrangement with Fort Worth radio station WBAP, which was maintained as the latter operated at various frequencies; it originally began in 1922, when WBAP (which first went on the air on May 2 of that year, nine weeks before WFAA began operations) transmitted at 630 kHz and continued until 1927, before resuming when that station moved to 800 kHz in 1929 and settling when WBAP moved its current frequency at 820 kHz in 1941. In 1947, WFAA and WBAP began time-sharing on a second frequency, 570 kHz, which was formerly occupied by KGKO. Until WFAA (AM) began to transmit full-time on 570 kHz in 1970, WBAP and WFAA were engaged in the somewhat bizarre situation of having to switch back and forth between the 570 and 820 frequencies at various times of the day: WBAP broadcast on 820 AM from midnight to 6:00 a.m., with WFAA taking over the frequency space until noon; WBAP returned to the 820 signal for a few hours, before WFAA once again took over the frequency. WFAA had control over 820 during prime evening hours, when the 50,000-watt clear channel signal could often be heard as far west as California and as far east as New York (at the time, there were significantly fewer radio stations that were operating at night, reducing the likelihood of interference).