FM broadcasting
VHF Radio waves do not travel far beyond the visual horizon, so reception distances for FM stations are usually limited to 30–40 miles (50–65 km) They can also be blocked by hills or buildings.
City of license
While becoming less meaningful over the decades, stations are still required to post a public file somewhere within 25 miles of the city, and to cover the entire city with a local signal. In the United States, a station's transmitter must be located so that it can provide a strong signal over nearly all of its "principal community" (5 mV/m or stronger at night for AM stations, 70 dbuV for FM, 35 dbu for DTV channels 2-6, 43 dbu for channels 7-13 and 48 dbu for channels 14+), even if it primarily serves another city. For example, American television station WTTV primarily serves Indianapolis; however, the transmitter is located farther south than the other stations in that city because it is licensed to Bloomington, 50 miles south of Indianapolis. In some cases, such as Jeannette, Pennsylvania-licensed WPCW 19, the FCC has waived this requirement; the station claimed that retaining an existing transmitter site 25.6 miles southeast of its new community of license of Jeannette would be in compliance with the Commission's minimum distance separation requirements (avoiding interference to co-channel WOIO 19 Shaker Heights). Another extreme example of a station's transmitter located far from the city of license is the FM station KPNT, formerly licensed to Ste. Genevieve, Missouri and transmitting from Hillsboro, but serving the St. Louis and Metro East market to the north. In 2015, the station was allowed by the FCC to move their city of license to Collinsville, Illinois and have a transmitter in St. Louis proper with a power decrease.