This is one of those oddities of radio syndication, made more interesting by technology. Rush Limbaugh offers “exclusivity” to its affiliates. If your station signs with Rush, nobody in your market is allowed to carry the show – it might bleed in from a distant market, but not a direct competitor.
The FCC has rules prohibiting network exclusivity – probably dating back to the early days when NBC’s Red and Blue networks dominated radio (pre Workd War Two)
Here is the actual rule – there are separate rules for AM and FM that say essentially the same thing
Specifically
§ 73.132 Territorial exclusivity.
No licensee of an AM broadcast station shall have any arrangement with a
network organization which prevents or hinders another station serving substantially the same area from broadcasting the network’s programs not taken by the former station, or which prevents or hinders another station serving a substantially different area from broadcasting any program of the network organization: Provided, however, That this section does not prohibit arrangements under which the station is granted first call within its primary service area upon the network’s programs. The term ‘network organization’ means any organization originating program material, with or without commercial messages, and furnishing the same to stations interconnected so as to permit simultaneous broadcast by all or some of them. However, arrangements involving only stations under common ownership, or only the rebroadcast by one station or programming from another with no compensation other than a lump-sum payment by the station rebroadcasting, are not considered arrangements with a network organization. The term ‘arrangement’ means any contract, arrangement or understanding, expressed or implied.
If you carry Rush Limbaugh, Premiere Radio demands that you not only carry Sean Hannity, but also carry those short form broadcasts during the morning local shows.
So what if I am not the station with Rush and Hannity, but I want to carry America Now with Me, Meghan McCain which the other station doesn’t carry. This rule says Premiere may not hinder me from affiliating with Premiere to carry America Now.
The station carrying Rush and Hannity cannot demand that Premiere not allow me to carry John McCain’s daughter. Premiere can say their affiliate has “first call” IF they decide to carry the show – but if they decline to take the show, Premiere can offer the show to competitors.
But what if the Premiere affiliate decides to take only one hour and plays it at 3 AM on an AM station that only is allowed to use 4 watts after the sun sets?