To broadcast radio or TV signals in the United States, an owner or operator must obtain a license from the FCC. The FCC licenses all transmitters whose signal can travel distances, although there are a few exceptions for very low power radio transmitters, such as those in CB radios and walkie-talkies.
The FCC licenses radio transmitters according to geography and certain other common ownership rules that are intended to help prevent radio stations from interfering with the signals of other stations. The spectrum of available radio and television frequencies is limited, so the FCC can issue only a limited number of licenses. Therefore, broadcast licenses are extremely valuable, particularly in large cities.
The FCC limits individuals or corporate entities from acquiring more than a certain number of stations in order to promote diverse viewpoints over the airwaves. The Telecommunications Act of 1996 relaxed these limits, sparking a wave of recent broadcast mergers and acquisitions.