Of course, as with WOWC-FM, licensed to Jasper, a station may serve another market, in this case Birmingham. A station must pick a city within it's protected contour as it's city of license. I don't know why. Power FM stations in the US are limited to a maximum of 100,000 watts. AM stations are limited to 50,000 watts.
Television is a little more complex.
Stations with unusually high antennas are often restricted to lesser power levels. FM translators are limited to 250 watts. I am not sure what the limit is on TV translators. Even with only an antenna at 500 or so foot HAAT, they still have quite a coverage area. HAAT Height Above Average terrain differs from height AMSL, or above sea level.