Radio stations that specialized in rock music recorded during the later 1960s, 1970s, and 1980s were generally labeled Album-Oriented Rock (AOR) stations. The symbiosis between AOR stations and bands such as Deep Purple, Led Zeppelin, and Aerosmith has led many to refer to virtually all 1970s era hard rock bands as AOR as well. When it was first introduced in the late 1960s, the AOR format was only marginally commercial, but by the mid-1970s AOR stations were taking on many of the characteristics of top-40 stations. As the popularity of AOR stations grew, major label record companies exerted increasing influence over AOR playlists around the country, in the process squeezing out competition from independent label competitors. A by-product of this influence peddling was a creeping homogenization of rock music available on radio stations.

The AOR format was happened upon after the Federal Communication Commission (FCC...