In 1966 the Federal Communications Commission ruled that major market FM radio stations could no longer simulcast their AM sister stations. FM had to become separate with individual programming. This was deemed necessary to allow FM to grow and develop its own audience. The ruling put radio station owners in a bind. They needed to come up with new formats for these weaker and less desirable stations. Since FM was more difficult to receive, its universe of potential listeners was much smaller... and so was its billing. The new formats therefore had to be both different and relatively inexpensive to program. It was in that environment that RKO General Broadcasting launched its new WOR-FM (98.7Mhz) “Hot 100” format on July 30, 1966. The name is deceiving because, in fact, it was the first progressive rock station in the country. It marketed itself as stereo as a way to distinguish itself from AM radio. The problem was that many of the records played by the station were not in stereo. While it was true that most record albums were stereo, singles were not. Since the singles came out before the albums, much of the new music it was breaking was in mono.