An added bit of confusion for those interested in the early history of radio in North America is a treaty called the North American Radio Broadcasting Agreement, usually referred to as ``NARBA'', which rearranged the radio dial substantially. The rationale behind the treaty was to set aside Canadian (and Mexican) clear channel frequencies throughout the dial, at a rate of about one per 100 kHz. The treaty also expanded the band from 1500 kHz to 1600 kHz; it took effect on March 29, 1941. This agreement is no longer in force; it has been superseded by US-Canada and US-Mexico working arrangements made in the early 1980s, as well as an ITU-sponsored agreement covering all of the Western Hemisphere.

Here are the most significant changes:

  • 540: new Canadian clear
  • old 550-680: unchanged
  • old 690: mostly unchanged, except CFRB to 860
  • old 700-730: unchanged
  • 740: new Canadian clear
  • old 740-780: moved up 10 kHz to 750-790
  • 800: new Canadian clear
  • old 790-830: moved up 20 kHz to 810-850
  • 860: new Canadian clear
  • old 850-870: moved up 20 kHz to 870-890
  • 900: new Canadian clear
  • old 880-970: moved up 30 kHz to 910-1000
  • 1010: new Canadian clear
  • old 980: KDKA to 1020
  • old 990: WBZ to 1030
  • old 1000: WHO to 1040
  • old 1010: KQW [KCBS] to 740 (but not right away)
  • old 1020: KYW to 1060
  • old 1030: CFCN to 1010, CKLW to 800
  • old 1040: WTIC, KRLD, KWJJ all to 1080
  • old 1050: to 1070
  • old 1060: WBAL to 1090, WJAG to 1110 (later traded for 780 with KFAB)
  • old 1070-1150: moved up 30 kHz to 1100-1180
  • old 1160: WOWO to 1190, WWVA to 1170
  • old 1170: WCAU [WGMP] to 1210
  • old 1180: KEX to 1190, KOB [KKOB] to 770, WDGY [KFAN] to 1130, WINS to 1010
  • old 1190: WOAI to 1200, WSAZ to 930, WATR to 1320
  • old 1200-1450: moved up 30 kHz to 1230-1480
  • old 1460: KSTP, WSJV [WTOP] to 1500
  • old 1470: KGA, WLAC, WMEX [WWZN] to 1510
  • old 1480: KOMA, WKBW [WWKB] to 1520
  • old 1490: KFBK, WCKY [WSAI] to 1530
  • old 1500: to 1490
  • old 1510: CFRC to 1490
  • old 1530: W1XBS to WBRY [WQQW;dark] 1590, W9XBY to KITE [dark] 1550
  • old 1550: W2XR to WQXR [WQEW] 1560, W6XAI to KPMC [KNZR] 1560
  • 1580: new Canadian clear