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 implementaion 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.

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.

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.