This is the General History Section of
The Broadcast Archive

Maintained by:
Barry Mishkind - The Eclectic Engineer


by Mark Durenberger
Minneapolis, Minnesota

This is the third in a series of 6 articles about the history of clear-channel AM radio stations.  

When last we met, we reviewed early attempts on the part of full-service broadcasters to secure “super-power” authorization, and we looked at WLW’s 500,000-watt Special Temporary Authority on 700 kc/s.  The requests for super-power were actually stimulated by the FCC’s public comments, as they positioned for the North American Regional Broadcasting Agreement of 1941.  The goal of NARBA 1941 was “radio standardization throughout the Western Hemisphere.” The planning for the conference began in the mid-1930s. The super-power positioning took place against the noisy backdrop of powerful “border blasters” operating out of Mexico and interfering with some U.S. broadcast signals.  The U.S. delegation wanted to reserve the ability to fight the border blasters with its own super-power arsenal if need be. They also had to balance the interests of powerful clear-channel broadcasters against Congress and the “have-nots” who saw super-power in the hands of the few as further undue media concentration.


NARBA changes

The U.S. delegation went into the conference with a list of 25 frequencies they wanted protected for single-station use (including possible super-power), and they listed 21 additional 50-kilowatt channels that could be duplicated. For the first time, the labels 1-A and 1-B were officially applied to U.S. authorizations. 1-A stations were to continue operating non-directional, with solo nighttime assignments. The 1-B channels were to be occupied by two or more stations at 50 kW maximum, usually employing directional antennas to protect each other. Interference from other countries would be accepted on the 1-Bs, even within U.S. borders. Interference protection for the 1-As was to be much more extensive, as we’ll see.


Intriguing language

In the interests of their own super-power stations, some member nations of NARBA pushed a curious turn of phrase into the final Agreement. That verbiage would be cited in the ensuing clear-channel discussions in this country.  The NARBA language essentially stated that while 1-B stations were given a maximum authorized power of 50 kW, the 1-As would be authorized a minimum power of 50 kW.  In this respect, the minimum vocabulary the U.S. endorsed as a signatory to NARBA would differ from the FCC’s own 50-kW maximum language. In exchange for this subtlety, the United States gained a major concession from its neighbors. 1-A co-channel stations in adjoining countries could be located no closer than 650 miles from that country’s common boundary with the United States. By geographical happenstance this language prohibited, with few exceptions, any co-channel operation on U.S. 1-A channels anywhere in North America.  When the delegates returned home, the United States had its continued protection on 25 1-A channels.  To answer the demand for more frequencies, the United States agreed to an expansion of the band to 1600 kc/s. What was not resolved at the1941 NARBA was the U.S. position on super-power on the 1-A channels.


The great dial switch

To implement the NARBA changes, the United States participated in a major frequency re-shuffle.  On March 29, 1941, many of this country’s AM stations moved to a new dial location, where they’ve been since. Most stations moved up the band, from 10 to 30 kc/s, but few did much to their plants, other than retuning and changing crystals.  As a result, there exists today a number of stations whose towers are slightly longer than optimum for their present operating frequency!

With the 1941 NARBA behind them, FCC staffers could now turn to the issue of providing reliable nighttime service to the country’s “white areas.” Attempts to build a record on the white area issue surfaced as early as an October 1936 FCC hearing, but it was on Feb. 20, 1945, that the FCC officially opened Docket 6741, looking into the future of clear channel broadcasting.  Thus began a struggle that was to last 35 years and put a lot of consultants’ and attorneys’ kids through college.


Engineering and economic advice

As it opened the clear-channel proceeding, the FCC requested industry input on the coverage issues. Industry-Advisory engineering committees met at length and reported out several ideas.  First, they suggested there was a need for at least four national night-time services. But the committees also agreed it was impractical to deliver four solid nighttime services across the country with only four stations on four channels, and they suggested that some form of duplication would be needed. What was left to be resolved was how to get to that goal.  The advisors also ventured into economic matters, arguing that super-power operation, while seemingly successful in other countries where it was usually subsidized, might not do well under the economic model of U.S. broadcasting. It was suggested that the cost to cover wide areas of low population density might not be covered by the advertising dollars available in those areas. The report compared wide-area night-time sky-wave service to Rural Free Delivery, in which mail costs are borne primarily by the urban centers, and the costs of serving remote constituents are essentially subsidized. 

The committees concluded that primary operating support for super-power stations would have to come from “urban centers” where the stations would presumably have to be located. Looking at a U.S. map and applying some logic, one could conclude there might not be enough large “urban centers” in the sparsely-populated white areas to support super-power operation. Therefore, if cost-support was to be a driver, re-locating super-power stations, away from urban centers, would not be the best approach.

That economic argument alone might have doomed the chances for super-power. For this reason and others, the FCC stayed focused on duplicating the 1-A clear channels. The commission was very clear in stating that the ultimate solution for white-area coverage had to meet one primary criterion: maximum population gain. (In fact, when later it began to authorize such duplicate assignments, it declined to name specific cities for the new signals but instead identified only the states in which such operations might be located.)


What next?

In the late 1940s and early 1950s, proposals on how to deal with the clears appeared with regularity. It is interesting to watch the disparate interests at play during this proceeding.

There were those who honestly saw a strong need for new service to white areas. Others were interested only in bringing about the dissolution of the 1-As. Both groups had sympathetic ears at the FCC. Some of the commission’s public statements during this period make fascinating reading, as you watch the FCC slowly move toward the politically comfortable position that “more stations are better for you.” Our story will be served by notes from the record, as the clear-channel docket was being assembled:


In 1946 the FCC decided to allow “Daytimers” to operate on the 1-As, but only inside a 750-mile radius of the 1-A stations (the approximate 50/50 skywave contour). They reasoned that assignments outside that contour could preclude possible high-power operation or duplication on the channel. In granting Daytimers authorization to operate on the clear channels, the FCC enabled a breed of political fighters who got a taste of the action and who would exert a sometimes ill-advised influence on the coming battles.

In 1948, CBS proposed that FM stations be taken into account in defining white-area service. CBS reminded the FCC that its own staff had reported that “new FM assignments will provide service to 500 new communities, in every state except Montana.”  The FCC wouldn’t buy CBS’s argument. They said, “Clear channels would always be needed for wide-area service, under any foreseeable developments affecting the wider utilization of FM radio.”  It would be many years before the FCC would include FM in calculating radio coverage.

During this period, the FCC poked its toes into the water with a series of tentative “proposals.” In 1958 the Commission suggested adding new (Western-states) Class I stations on 660, 770, 880, 1100 and 1180. They also wanted new Class II assignments on 670, 720, 780, 890, 1020, 1120 and 1210 in areas “where they were needed.”

 The FCC made this proposal while at the same time suggesting that it would leave the other 1-As protected for higher-power operation.  It’s small wonder that industry-watchers were becoming confused.

Mark Durenberger  welcomes questions and comments about this series via e-mail to