General Order 40

General Order 40 was an order issued on August 30, 1928 by the new Federal Radio Commission under the Radio Act of 1927 which provided for a reallocation of the commercial broadcast radio spectrum.

As a result of implementation of General Order 40, most U.S. radio stations were forced to change their broadcast frequencies. The frequency changes went into effect at 3:00 a.m. Eastern time on November 11, 1928.

File:Federal Radio Commission General Order 40 Map.png

Five U.S. zones used for frequency allocation

The goals of the FRC in reallocating the frequencies were to reduce interference and "clutter" on the air, to provide better access to the airwaves to smaller cities, and "underserved" areas, and to rid the air of "temporary" and "portable" stations. This was achieved by designating each frequency as either a frequency for one (or more) clear-channel stations broadcasting with maximum power, a frequency to be shared by regional stations with less power, or a frequency to be shared by many local stations with limited power. Each clear channel frequency was reserved for one principal station in one of five U.S. zones or in Canada. Some of these clear frequencies were shared with one or more lower power stations in locations remote from the principal station. The U.S. was divided into the five zones used by the Radio Act of 1927, as shown on the map to the right.

The allocation scheme introduced by General Order 40 stayed in place for over twelve years, until the implementation of the North American Radio Broadcasting Agreement in March 1941.

Stations show in bold are the original 1928 Band Plan internationally cleared station primary allocations. Station(s) on the same frequency are either: 1) shared allocations, 2) daytimers, or 3) secondary stations which eventually achieved full-time status, but at lower power or highly directionalized so as to protect the primary station.

The table below presents a general outline of the frequency allocations under the order. For "Clear" frequencies, the zone allocated to the principal station on that frequency is given, along with the principal station that actually occupied the frequency, the previous frequency of the actual principal station, and other stations that shared the frequency. Station call signs shown in parentheses are stations owned by the same licensee of the principal station on that frequency.

Freq. (kHz)	Used for	Max. Power (watts)	Zone	Principal station(s)		Other stations sharing frequency (zone)
				Calls, City	Prev. freq.
550	Regional	1000	—	—	—	7 U.S. stations
560	Regional	1000	—	—	—	10 U.S. stations
570	Regional	1000	—	—	—	11 U.S. stations
580	Regional	1000	—	—	—	6 U.S. stations 8 Canadian stations
590	Regional	1000	—	—	—	5 U.S. stations
600	Regional	1000	—	—	—	7 U.S. stations 3 Canadian stations
610	Regional	1000	—	—	—	5 U.S. stations
620	Regional	1000	—	—	—	6 U.S. stations
630	Regional	1000	—	—	—	4 U.S stations 3 Canadian stations
640	Clear	TBD	5	KFI, Los Angeles	640	WOI, Ames, IA (4) WAIU, Columbus, OH (2)
650	Clear	TBD	3	WSM, Nashville	890	KPCB, Seattle (5)
660	Clear	TBD	1	WEAF, New York	610	WAAW, Omaha (4)
670	Clear	TBD	4	WMAQ, Chicago	670	none
680	Clear	TBD	5	KPO, San Francisco	710	KFEQ, St. Joseph, MO (4) WPTF, Raleigh (3)
690	Clear		Canada	CFRB, Toronto		CJCJ, Calgary
700	Clear	TBD	2	WLW, Cincinnati	700	none
710	Clear	TBD	1	WOR, New York (Newark, NJ)	710	KMPC, Los Angeles (5)
720	Clear	TBD	4	WGN/(WLIB), Chicago	720	none
730	Clear		Canada	CKAC, Montreal		CKWX, Vancouver
740	Clear	TBD	3	WSB, Atlanta	630	KMMJ, Clay Center, NE (4)
750	Clear	TBD	2	WJR, Detroit	680	none
760	Clear	TBD	—	WJZ, New York (Newark, NJ)	660	WEW, St. Louis KVI, Tacoma
770	Clear	TBD	4	WBBM/(WJBT), Chicago	770	none
				KFAB, Lincoln, NE	940
780	Regional	1000	—	—	—	6 U.S. stations 3 Canadian stations
790	Clear	TBD	5	KGO, San Francisco (Oakland)	790	WGY, Schenectady (1)
800	Clear	TBD	3	WFAA, Dallas	550	none
				WBAP, Ft. Worth	600
810	Clear	TBD	4	WCCO, Minneapolis	740	WPCH, New York (1)
820	Clear	TBD	2	WHAS, Louisville	930	none
830	Clear	TBD	5	KOA, Denver	920	WRUF, Gainesville, FL (3) WHDH, Boston (1)
840	Clear		Canada	CFCA/CNRT, Toronto
850	Clear	TBD	3	WWL, New Orleans	1220	none
				KWKH, Shreveport	760
860	Clear	TBD	1	WABC/(WBOQ), New York	970	WHB, Kansas City (4) KMO, Tacoma (5)
870	Clear	TBD	4	WLS, Chicago	870	none
				WENR/(WBCN), Chicago	1040
880	Regional	1000	—	—	—	7 U.S. stations 7 Canadian stations
890	Regional	1000	—	—	—	9 U.S. stations
900	Regional	1000	—	—	—	7 U.S. stations
910	Clear		Canada	CFCF/CHYC, Montreal		CKY, Winnipeg CJAT, Trail, BC
920	Regional	1000	—	—	—	6 U.S. stations
930	Regional	1000	—	—	—	8 U.S. stations 5 Canadian stations
940	Regional	1000	—	—	—	6 U.S. stations
950	Regional	1000	—	—	—	4 U.S. stations
960	Clear	—	Canada	CFRB, Toronto		CFRN, Edmonton
970	Clear	TBD	5	KJR, Seattle	970	WCFL, Chicago (4)
980	Clear	TBD	2	KDKA, Pittsburgh	960	none
990	Clear	TBD	1	WBZ, Springfield, MA / WBZA, Boston	910	none
1000	Clear	TBD	4	WHO, Des Moines	560	KFVD, Los Angeles (5)
				WOC, Davenport	800
1010	Regional	1000	—	—	—	7 U.S. stations 2 Canadian stations
1020	Clear	TBD	2	KYW/(KFKX), Chicago (4)	570	WRAX, Philadelphia (2)
1030	Clear		Canada	CFCF, Montreal		CNRV, Vancouver
1040	Clear	TBD	3	KRLD, Dallas	650	KTHS, Hot Springs, AR (3) WKAR, East Lansing, MI (2) WMAK, Buffalo (1)
1050	Clear	TBD	5	KNX, Los Angeles	890	KFKB, Milford, KS (4)
1060	Clear	TBD	1	WBAL, Baltimore	1050	WJAG, Norfolk, NE (3) KWJJ, Portland, OR (5)
				WTIC, Hartford	560
1070	Clear	TBD	2	WTAM/(WEAR), Cleveland	750	KJBS, San Francisco (5) WCAZ, Carthage, IL/ WDZ, Tuscola, IL (4)
1080	Clear	TBD	3	WBT, Charlotte	1160	WMBI / WCBD, Chicago (4)
1090	Clear	TBD	4	KMOX, St. Louis	1000	none
1100	Clear	TBD	1	WLWL, New York	810	KGDM, Stockton, CA (5)
				WPG, Atlantic City, NJ	1100
1110	Clear	TBD	2	WRVA, Richmond	1180	KSOO, Sioux Falls, SD (4)
1120	Regional	1000	—	—	—	10 U.S. stations 4 Canadian stations
1130	Clear	TBD	5	KSL, Salt Lake City	990	WJJD, Chicago (4) WOV, New York (1)
1140	Clear	TBD	3	WAPI, Birmingham	880	none
				KVOO, Tulsa	860
1150	Clear	TBD	1	WHAM, Rochester	1070	none
1160	Clear	TBD	4	WOWO, Ft. Wayne	1310	none
				WWVA, Wheeling, WV (2)	580
1170	Clear	TBD	2	WCAU, Philadelphia	1150	KTNT, Muscatine, IA (4)
1180	Clear	TBD	5	KEX, Portland, OR	1080	WDGY/WHDI, Minneapolis
				KOB, Albuquerque	760
1190	Clear	TBD	3	WOAI, San Antonio	1070	WICC, Bridgeport, CT (1)
1200	Local	100	—	—	—	48 U.S. stations
1210	Local	100	—	—	—	44 U.S. stations 5 Canadian stations
1220	Regional	1000	—	—	—	6 U.S. stations
1230	Regional	1000	—	—	—	8 U.S. stations
1240	Regional	1000	—	—	—	3 U.S. stations
1250	Regional	1000	—	—	—	12 U.S. stations
1260	Regional	1000	—	—	—	6 U.S. stations
1270	Regional	1000	—	—	—	10 U.S. stations
1280	Regional	1000	—	—	—	6 U.S. stations
1290	Regional	1000	—	—	—	7 U.S. stations
1300	Regional	1000	—	—	—	12 U.S. stations
1310	Local	100	—	—	—	53 U.S. stations
1320	Regional	1000	—	—	—	6 U.S. stations
1330	Regional	1000	—	—	—	5 U.S. stations
1340	Regional	1000	—	—	—	4 U.S. stations
1350	Regional	1000	—	—	—	5 U.S. stations
1360	Regional	1000	—	—	—	8 U.S. stations
1370	Local	100	—	—	—	42 U.S. stations
1380	Regional	1000	—	—	—	4 U.S. stations
1390	Regional	1000	—	—	—	4 U.S. stations
1400	Regional	1000	—	—	—	9 U.S. stations
1410	Regional	1000	—	—	—	11 U.S. stations
1420	Local	100	—	—	—	38 U.S. stations
1430	Regional	1000	—	—	—	7 U.S. stations
1440	Regional	1000	—	—	—	9 U.S. stations
1450	Regional	1000	—	—	—	9 U.S. stations
1460	Super Regional	5000	2	WJSV, Washington, DC	1480	none
			4	KSTP, St. Paul	1360
1470	Super Regional	5000	3	WLAC/WTNT, Nashville	1330	none
			5	KGA, Spokane	1150
1480	Super Regional	5000	1	WKBW, Buffalo	1380	none
			3	KFJF, Oklahoma City	1100
1490	Super Regional	5000	1	WFBL, Syracuse NY	1160	none
			2	WCKY, Cincinnati (Covington, KY)	none
			4	WHT/WORD/WJAZ, Chicago	var.
1500	Local	100	—	—	—	31 U.S. stations

General Order resulted in several instances in which two stations were forced to share the same frequency:

• WFAA in Dallas and WBAP in Fort Worth were forced to share a clear channel frequency at 800 kHz. Eventually, both stations also obtained a regional frequency which they also shared. As a result, these two stations operated alternately on two different frequencies for many years.
• WLS and WENR, both Chicago, also had to share a frequency at 870 kHz. This continued until 1959 when ABC purchased both stations.
• WHO in Des Moines and WOC in Davenport were forced to share the single clear channel frequency at 1000 kHz which was allocated for the state of Iowa. Both stations fought the shared allocation and lost. Eventually WHO bought out WOC and consolidated operations in Des Moines.
• KFAB in Lincoln, Nebraska shared the 770 frequency with WBBM in Chicago. To avoid interference, KFAB was forced to carry the same network programming as WBBM at night and to synchronize its transmissions.
• WBAL in Baltimore and WTIC in Hartford shared the 1070 frequency.
• WOWO in Fort Wayne and WWVA in Wheeling shared the frequency at 1160 kHz.
• At 850 kHz KWKH in Shreveport and WWL in New Orleans shared the single frequency allocated to Louisiana.

The 790 kHz clear channel frequency was allocated to zone 5, and General Electric's KGO in Oakland received the assignment for this frequency, but GE was also able to use the frequency for its stronger station WGY in Schenectady. The 1020 kHz frequency was assigned to zone 2, but the strongest station licensed on the frequency was KYW in Chicago, not WRAX in Philadelphia; this was resolved when KYW moved to Philadelphia in 1934, forcing WRAX to move to the regional frequency of 920 kHz, sharing time with WPEN which was already there.

See also

• North American Radio Broadcasting Agreement
• Federal Radio Commission

External links

• Actual text of General Order 40 contained in Radio Service Bulletin No. 137, pp. 9–10, August 31, 1928
• Behind the Clear Channel Matter, a series of six articles about the history of clear-channel AM radio stations, by Mark Durenberger