North American Radio Broadcasting Agreement

North American Radio Broadcasting Agreement

The North American Radio Broadcasting Agreement, usually referred to as NARBA, is a treaty that took effect in March 1941 and set out the bandplan and interference rules for mediumwave AM broadcasting in North America. Although mostly replaced by other agreements in the 1980s, the basic bandplan of NARBA has remained to the present day. Among its major features were the extension of the broadcast band from its former limit of 1500 kHz to 1600 kHz, (now 1700  kHz) and the shift of most existing AM stations' frequencies to make room for additional clear-channel station allocations for Canada and Mexico.[1]

The agreement eventually governed AM band use in the United States, Canada, Mexico, Cuba, the Dominican Republic, and Haiti.[citation needed] In accordance with the treaty, clear channel frequencies were set aside across the radio dial, at a rate of about one per 100 kHz, and the 1230, 1240, 1340, 1400, 1450, and 1490 channels were reserved mainly for local stations. The agreement also officially expanded the upper limit of the AM broadcast spectrum from 1500 kHz to 1600 kHz. It required that most existing AM stations change frequencies, resulting in a massive shuffling of radio station dial positions.



Although a 1933 conference on the subject failed, a 1937 North American Radio Conference in Havana agreed on the principles for frequency allocations. In late 1937, the Inter-American Radio Conference agreed to protect U.S. AM stations by eliminating Mexican border blasters. In mid-1938, the United States Senate ratified the Havana treaty and asks for it to take effect a year after the treaty is ratified by three of the four participating countries of Canada, Cuba, Mexico, and the U.S. At first, the Mexican Senate refused to ratify. Nevertheless, the U.S. and Canada completed a frequency agreement in 1939, based on the Havana Treaty, and Mexico ratified the NARBA treaty at the end of the year.[2]

In the United States, the new frequencies took effect at 3:00 a.m. Eastern[1] on 29 March 1941.[2]

A three-year NARBA agreement in 1946 gave Cuba five U.S. clear channel allocations. A November 1950 NARBA agreement, signed by the Bahamas, Canada, Cuba, the Dominican Republic, Jamaica and the U.S., gave Cuba the right to use six, and Jamaica two, U.S. clear channel allocations.[2]

Frequency changes

Among the most significant changes were:

Old Freq.
Station(s) Moved
New Freq.
540 CBK unchanged 540 Canadian clear
550-680 all unchanged 550-680
690 all, except CFRB unchanged 690 Canadian clear
CFRB 860
700-720 all unchanged 700-720
730 all, except CFPL unchanged 730
CFPL 1570
new Canadian clear 740 allocated to CBL which moved from 840
740-790 all up 10 750-790
new Canadian clear 800 allocated to CKLW which moved from 1030
790-830 all up 20 810-850
840 CBL 740
new Canadian clear 860 allocated to CFRB
850-870 all up 20 870-890
new Canadian clear 900 allocated to CHML (and CJBR)
880-970 all up 30 910-1000
980 KDKA up 40 1020
990 WBZ up 40 1030
1000 WHO up 40 1040
1010 KQW (now KCBS) 740 KQW did not move until 1947
1020 KYW up 40 1060
1030 CFCN (now CBR) down 20 1010
CKLW 800
1040 WTIC
up 40 1080
1050 all up 20 1070 CBA became a new Canadian clear on 1070
1060 WBAL up 30 1090
WJAG up 40 1110 this was later traded for 780 with KFAB
1070–1150 all up 30 1100–1180
1160 WOWO up 30 1190
WWVA up 10 1170
1170 WCAU (now WPHT) up 40 1210
1180 KEX up 10 1190
KOB (now KKOB) 770
WDGY (now KFAN) down 50 1130
WINS 1010
1190 WOAI up 10 1200
WSAZ 930
WATR 1320
1200–1450 all up 30 1230–1480
1460 KSTP
up 40 1500
1470 KGA
up 40 1510
1480 KOMA
up 40 1520
1490 KFBK
up 40 1530
1500 all down 10 1490
1510 CKCR (later CHYM) down 20 1490
1530 W1XBS to WBRY
(later WTBY, then WQQW; now dark)
up 60 1590 Since 1934 U.S. frequencies above 1500 had been
allocated only to four experimental stations that
broadcast with a signal 20 kHz wide for "high fidelity."
The stations were converted to regular broadcasting
(and regular call signs) with the NARBA frequency
(now dark)
up 20 1550
1550 W2XR to WQXR
(now WQEW)
up 10 1560
(now KNZR)
up 10 1560
new Canadian clear 1570 allocated to CFPL (AM)

Current status

NARBA has been substantially superseded by the Regional Agreement for the Medium Frequency Broadcasting Service in Region 2 (which was signed in Rio de Janeiro in 1981 and took effect on 1 July 1983 at 08:00 UTC). The interference protection criteria in the Rio agreement are significantly different from NARBA, particularly in that the concept of clear-channel stations is eliminated. NARBA countries the Bahamas, Canada, Mexico, and the United States are also signatories of the Rio agreement. In that agreement, the Bahamas and Canada also declared their intent to denounce NARBA.[3] However, NARBA still officially remains in effect between the Bahamas, Dominican Republic, and United States[4] because those countries have not formally abrogated NARBA.[5] The United States also has bilaterial agreements with Canada and with Mexico: the Agreement Between the Government of the United States of America and the Government of Canada Relating to the AM Broadcasting Service in the Medium Frequency Band (1984) and the Agreement Between the Government of the United States of America and the Government of the United Mexican States Relating to the AM Broadcasting Service in the Medium Frequency Band (1986).[5]

See also

External links


  1. ^ a b Miller, Jeff (2010-05-01). "A Chronology of AM Radio Broadcasting 1900-1960". Retrieved 2010-05-11. 
  2. ^ a b c "Broadcasting Special Issue". Broadcasting. 1970-11-02. Retrieved 2010-05-11. 
  3. ^ Regional Administrative MF Broadcasting Conference (Region 2), Rio de Janeiro, 1981. ISBN 92-61 01311-2. Retrieved 2010-05-11.  Bahamas and Canada announce their intent to renounce NARBA in Final Protocol statement No. 4 on page 88.
  4. ^ 47 C.F.R. 73.1650. Retrieved 2010-05-11.
  5. ^ a b "1997 Report on International Negotiations and Notifications Concerning Radio Services". Washington, D.C.: Federal Communications Commission (Planning & Negotiations Division, International Bureau). July 1997. Retrieved 2010-05-11. 

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