Editing FM broadcast band (section)

===ITU Region 2 bandplan and channel numbering===
The original frequency allocation in [[North America]] used by [[Edwin Armstrong]] used the frequency band from 42 through 50&nbsp;MHz, but this allocation was changed to a higher band beginning in 1945. In [[Canada]], the [[United States]], [[Mexico]], [[the Bahamas]], etc., there are 101 [[List of channel numbers assigned to FM frequencies in North America|FM channels]] numbered from ''200'' (center frequency 87.9&nbsp;MHz) to ''300'' (center frequency 107.9&nbsp;MHz), though these numbers are rarely used outside the fields of [[radio engineering]] and government.
 
The center frequencies of the FM channels are spaced in increments of 200&nbsp;kHz. The frequency of 87.9&nbsp;MHz, while technically part of TV channel 6 (82 to 88&nbsp;MHz), is used by just two [[List of North American broadcast station classes|FM class-D]] stations in the United States. Portable radio [[tuner (radio)|tuner]]s often tune down to 87.5&nbsp;MHz, so that the same radios can be made and sold worldwide. [[Automobile]]s usually have FM radios that can tune down to 87.7&nbsp;MHz, so that TV channel 6's audio at 87.75&nbsp;MHz (±10&nbsp;kHz) could be received while driving. This is largely no longer possible due to the 2009 [[digital television in the United States|digital television transition]], though in 2023 the FCC authorized fourteen [[Channel 6 radio stations in the United States|low-powered Channel 6 television stations]] to continue to operate radio services indefinitely.

In the United States, the twenty-one channels with center frequencies of 87.9–91.9&nbsp;MHz (channels 200 through 220) constitute the ''[[reserved band]]'', exclusively for [[non-commercial educational]] (''NCE'') stations. The other channels (92.1&nbsp;MHz through 107.9&nbsp;MHz (Channels 221–300) may be used by both commercial and non-commercial stations.<ref>{{cite web |url=http://www.fcc.gov/topic/fm-radio |title=FM Radio {{!}} FCC.gov |website=www.fcc.gov |url-status=dead |archive-url=https://web.archive.org/web/20110519010722/http://www.fcc.gov/topic/fm-radio |archive-date=2011-05-19}}</ref> (Note that in Canada and in Mexico this reservation does not apply; Mexico introduced a reservation of 106.1–107.9&nbsp;MHz for community and indigenous stations in 2014, though dozens of stations are grandfathered due to lack of space to relocate them.)

Originally, the American [[Federal Communications Commission]] (FCC) devised a [[bandplan]] in which FM radio stations would be assigned at intervals of four channels (800&nbsp;kHz separation) for any one geographic area. Thus, in one area, stations might be at 88.1, 88.9, 89.7, etc., while in an adjacent area, stations might be at 88.3, 89.1, 89.9, 90.7 etc. Certain frequencies were designated for Class A only (see [[FM broadcasting]]), which had a limit of three [[kilowatt]]s of [[effective radiated power]] (ERP) and an [[antenna (radio)|antenna]] height limit for the center of radiation of 300 feet (91.4 m) height above average terrain ([[HAAT]]). These frequencies were 92.1, 92.7, 93.5, 94.3, 95.3, 95.9, 96.7, 97.7, 98.3, 99.3, 100.1, 100.9, 101.7, 102.3, 103.1, 103.9, 104.9, 105.5, 106.3 and 107.1. On other frequencies, a station could be Class B (50&nbsp;kW, 500 feet) or Class C (100&nbsp;kW, 2,000 feet), depending on which zone it was in.

In the late 1980s, the FCC switched to a bandplan based on a distance separation table using currently operating stations, and subdivided the class table to create extra classes and change antenna height limits to meters. Class A power was doubled to six kilowatts, and the frequency restrictions noted above were removed. As of late 2004, a station can be "squeezed in" anywhere as long as the location and class conform to the rules in the FCC separation table.<ref>{{cite web|url=http://www.fcc.gov/mb/audio/spacing/|title=separation table|website=fcc.gov|access-date=19 March 2018|archive-url=https://web.archive.org/web/20041213090705/http://www.fcc.gov/mb/audio/spacing/|archive-date=13 December 2004|url-status=dead}}</ref> The rules for second-adjacent-channel spacing do not apply for stations licensed before 1964.

In 2017, Brazil laid the groundwork to reclaim channels 5 and 6 (76.1–87.5&nbsp;MHz) for sound broadcasting use and required new radio receivers to be able to tune into the new [[FM extended band in Brazil|extended band]] ({{langx|pt|faixa estendida}}, abbreviated eFM). Five transmitters of public broadcaster [[Brazil Communication Company]] were the first extended-band stations to begin broadcasts on May 7, 2021.<ref>{{Cite news |last=Bucco |first=Rafael |date=2021-05-07 |title=EBC inaugura uso da banda estendida FM |language=pt-BR |trans-title=EBC inaugurates use of the FM extended band |work=Tele Síntese |url=https://www.telesintese.com.br/ebc-inaugura-uso-da-banda-estendida-fm/ |access-date=2021-05-29}}</ref>

In 2023, Chile announced the expansion of the FM band to 76-108 MHz as part of the analog TV shutdown, scheduled for April 2024.<ref>{{Cite press release |author=<!--Not stated--> |date=2023-05-16 |location=Chile |title=Gobierno anuncia ampliación de la banda FM otorgando mayor espacio a radios a nivel nacional |language=es-CL |trans-title=Government announces expansion of FM band, granting more space to radio stations nationwide |publisher=SUBTEL |url=https://www.subtel.gob.cl/gobierno-anuncia-ampliacion-de-la-banda-fm-otorgando-mayor-espacio-a-radios-a-nivel-nacional/ |access-date=2024-11-27}}</ref>