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Call signs in the United States are identifiers assigned to radio and television stations, which are issued by the
Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdicti ...
(FCC) and, in the case of most government stations, the National Telecommunications and Information Administration (NTIA). They consist of from 3 to 9 letters and digits, with their composition determined by a station's service category. By international agreement, all call signs starting with the letters K, N and W, as well as AAA-ALZ, are reserved exclusively for use in the United States. AM, FM, TV and shortwave broadcasting stations can request their own call letters, as long as they are unique. The FCC policy covering broadcasting stations limits them to call signs that start with a "K" or a "W", with "K" call signs generally reserved for stations west of the Mississippi River, and "W" limited to stations east of the river. Amateur stations can receive call signs starting with all of the letters "A", "K", "N" and "W". Formerly, prefixes beginning with "A" were exclusively assigned to U.S. Army stations and prefixes beginning with "N" to U.S. Navy stations.


Broadcasting stations

Although most transmitters regulated by the
Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdicti ...
(FCC) are issued call signs for their official identification, the general public is most familiar with the ones used by radio and TV broadcasting stations. However, there is a wide variety in how much emphasis stations give to their call signs; for some it is the primary way they establish public identity, while others largely ignore their call signs, considering a moniker or slogan to be more easily remembered by listeners (and those filling in diaries for the
Nielsen Audio Nielsen Audio (formerly Arbitron) is a consumer research company in the United States that collects listener data on radio broadcasting audiences. It was founded as the American Research Bureau by Jim Seiler in 1949 and became national by merging ...
ratings measurement). In the United States, the only time broadcasting stations are required to mention their call signs is during
station identification Station identification (ident, network ID or channel ID or bumper) is the practice of radio and television stations and networks identifying themselves on-air, typically by means of a call sign or brand name (sometimes known, particularly in th ...
announcements, made at a "natural break in programming" as close to the beginning of each hour as possible. Television stations have the option of displaying a small graphic or text ( "digital on-screen graphic" or "bug") at the bottom of the screen listing their call sign, community of license, and other identifying information. Sometimes station identification is displayed non-intrusively in small type during short promotions, either for an upcoming show or their next local newscast (even incorporating these identifications at the start of newscasts), that air just before the top of each hour. FM stations with HD Radio digital subchannels must individually identify each program stream, but do not need to do so in any particular form; most licensees use the form "WXXX HD2", but this is not part of their call sign. A few AM stations have had the same call letters for 100 years or more: KDKA in Pittsburgh, Pennsylvania, has been in continuous use since 1920, while WBZ in Boston, KYW in Philadelphia, and KWG in Stockton, California, all date back to 1921. At the other extreme, reflecting multiple changes in ownership and format, are stations which have changed call letters numerous times, for example
KXFN KXFN (1380 AM broadcasting, AM) is a radio station in St. Louis, St. Louis, Missouri. It is owned by Relevant Radio, Relevant Radio, Inc. and airs an English language Christian radio, Catholic radio format, format. The station has a colorful hist ...
in Saint Louis, Missouri, has switched ten times since 1925.


Call signs meanings

While the earliest radio call signs were randomly or sequentially assigned and intended merely to distinguish transmitters, they soon became an important part of a station's identity, and since the mid-1920s government regulators have allowed station owners to choose their own. Thousands of radio and TV stations have been established, with a wide variety of reasons for choosing particular call signs. Some common categories include: * Slogans: It is sometimes difficult to determine which came first: a station's call sign, or a slogan attached to it. However, some well-documented examples of call letters being chosen to reflect an existing slogan include: WGN and WGN-TV in Chicago, standing for "World's Greatest Newspaper", used by their original owner, the ''Chicago Tribune''; WIS in Columbia, South Carolina, the "Wonderful Iodine State";
WPTF WPTF (680 kHz) is a commercial AM radio station broadcasting a news/talk radio format. Licensed to Raleigh, the station serves the Research Triangle area of North Carolina. It is owned by the Curtis Media Group, with studios located on Highwo ...
, Raleigh, North Carolina, which references the motto of previous owner the Durham Life Insurance Company, "We Protect the Family" while Z88.3, in Central Florida prizes itself on its "Positive Hits", with the call-sign
WPOZ WPOZ (88.3 MHz) is a non-commercial, listener-supported FM radio station licensed to Orlando, and serving Central Florida. It is owned by the Central Florida Educational Foundation, Inc., and it broadcasts a Contemporary Christian radio forma ...
. * Owners: The major owned-and-operated stations of the
Big Three television networks In the United States, there are three major traditional commercial broadcast television networks — CBS (Columbia Broadcasting System), NBC (National Broadcasting Company), and ABC (American Broadcasting Company) — that due to their lon ...
ABC ABC are the first three letters of the Latin script known as the alphabet. ABC or abc may also refer to: Arts, entertainment, and media Broadcasting * American Broadcasting Company, a commercial U.S. TV broadcaster ** Disney–ABC Television ...
,
CBS CBS Broadcasting Inc., commonly shortened to CBS, the abbreviation of its former legal name Columbia Broadcasting System, is an American commercial broadcast television and radio network serving as the flagship property of the CBS Entertainm ...
and
NBC The National Broadcasting Company (NBC) is an American English-language commercial broadcast television and radio network. The flagship property of the NBC Entertainment division of NBCUniversal, a division of Comcast, its headquarters are l ...
— have traditionally had call signs reflecting the network abbreviations. Stations operated by schools and universities commonly incorporate their school's initials, including
WWVU-FM WWVU-FM is a College formatted broadcast radio station licensed to Morgantown, West Virginia, serving Eastern Monongalia County, West Virginia. WWVU-FM is owned and operated by West Virginia University. Known as U92 The Moose, WWVU-FM broadca ...
(West Virginia University, Morgantown), and
KUOM KUOM (770 AM) – branded ''Radio K'' – is a daytime-only non-commercial educational college/alternative rock radio station licensed to serve Minneapolis, Minnesota. KUOM covers the Minneapolis–Saint Paul metropolitan area, and extends its ...
(University of Minnesota, Minneapolis). * Locations: Three stations have call signs that fully spell out their community of license:
WACO-FM WACO-FM (99.9 MHz, "WACO 100") is a commercial FM radio station in Waco, Texas. It airs a country music radio format and is owned by iHeartMedia, Inc. The studios and offices are located on West Highway 6 in Southwest Waco. The transmitter is o ...
(Waco, Texas),
WARE Ware may refer to: People * Ware (surname) * William of Ware (), English Franciscan theologian Places Canada * Fort Ware, British Columbia United Kingdom * Ware, Devon *Ware, Hertfordshire * Ware, Kent United States * Ware, Elmore County ...
(Ware, Massachusetts) and
WISE-FM WISE-FM is a Public Radio formatted broadcast radio station licensed to Wise, Virginia, serving Norton, Coeburn and Clintwood in Virginia. WISE-FM is owned and operated by Virginia Polytechnic Institute and State University. The station broadc ...
(Wise, Virginia). Other stations reference their
community of license In American, Canadian, and Mexican broadcasting, a city of license or community of license is the community that a radio station or television station is officially licensed to serve by that country's broadcast regulator. In North American broad ...
or designated market area (DMA) with an abbreviation or initialism, such as
WRAL-TV WRAL-TV (channel 5) is a television station licensed to Raleigh, North Carolina, United States, serving as the NBC affiliate for the Research Triangle area. It is the flagship station of the locally based Capitol Broadcasting Company, which h ...
(Raleigh, North Carolina), or
WCSC-TV WCSC-TV (channel 5) is a television station in Charleston, South Carolina, United States, affiliated with CBS and owned by Gray Television. The station's studios are located in the West Ashley section of Charleston, and its transmitter is loca ...
(Charleston, South Carolina). * Numbers: Numerous television stations have chosen call letters that reference their channel number, either spelled out or using Roman numerals:
WDIV-TV WDIV-TV (channel 4) is a television station in Detroit, Michigan, United States, affiliated with NBC. It serves as the flagship broadcast property of the Graham Media Group subsidiary of Graham Holdings Company. WDIV-TV maintains studio facili ...
(channel 4, Detroit, Michigan,
WXII-TV WXII-TV (channel 12) is a television station licensed to Winston-Salem, North Carolina, United States, serving the Piedmont Triad region as an affiliate of NBC. It is owned by Hearst Television alongside Lexington-licensed CW affiliate WCWG (c ...
(channel 12, Winston–Salem, North Carolina),
KXII KXII (channel 12) is a television station licensed to Sherman, Texas, United States, serving the Sherman, Texas–Ada, Oklahoma market as an affiliate of CBS, MyNetworkTV, and Fox. Owned by Gray Television, the station maintains studios on Te ...
(also channel 12, Sherman, Texas), WIIC-TV (now
WPXI WPXI (channel 11) is a television station in Pittsburgh, Pennsylvania, United States, affiliated with NBC and owned by Cox Media Group. The station's offices and studios are located on Evergreen Road in the Summer Hill neighborhood of Pittsbur ...
) (channel 11, Pittsburgh),
WPVI-TV WPVI-TV (channel 6), branded on-air as 6 ABC, is a television station in Philadelphia, Pennsylvania, United States, airing programming from the ABC network. Owned and operated by the network's ABC Owned Television Stations division, the stati ...
(channel 6, Philadelphia),
WIVB-TV WIVB-TV (channel 4) is a television station in Buffalo, New York, United States, affiliated with CBS. It is owned by Nexstar Media Group alongside CW owned-and-operated station WNLO (channel 23). WIVB-TV and WNLO share studios on Elmwood Aven ...
(channel 4, Buffalo, New York),
WTWO WTWO (channel 2) is a television station in Terre Haute, Indiana, United States, affiliated with NBC. It is owned by Nexstar Media Group, which provides certain services to ABC affiliate WAWV-TV (channel 38) under joint sales and shared serv ...
(channel 2, Terre Haute, Indiana),
KIXE-TV KIXE-TV, virtual and VHF digital channel 9, is a Public Broadcasting Service (PBS) member television station licensed to Redding, California, United States, and also serving Chico. The station is owned by the Northern California Educationa ...
(channel 9, Redding, California - And the last letter selected as it was part of the Educational network, now PBS). Some, like
WGRZ WGRZ (channel 2) is a television station in Buffalo, New York, United States, affiliated with NBC and owned by Tegna Inc. The station's studios are located on Delaware Avenue in downtown Buffalo, and its transmitter is located on Warner Hill ...
(channel 2, Buffalo) and
WDIO-DT WDIO-DT (channel 10) is a television station in Duluth, Minnesota, United States, affiliated with ABC and owned by Hubbard Broadcasting. The station's studios and transmitter are located on Observation Road in Duluth. WIRT-DT (channel 13) in ...
(channel 10, Duluth), use letters which have similarities to numerals; in those examples, the "Z" in WGRZ resembles a "2", while the "IO" in WDIO resembles a "10". Examples on the AM band have historically included
KIXI KIXI (880 AM) is a radio station licensed to Mercer Island/ Seattle, Washington. It operates 24 hours a day with a daytime power of 50,000 watts and a nighttime power of 10,000 watts from a transmitter in Mercer Slough Nature Park in Bellevue, ...
in Seattle, which previously broadcast at 910 kHz ("IX-I"); and KIIS (now KEIB) in Los Angeles, which originated on 1150 kHz (as the letters IIS resemble 115, its frequency in myriahertz).


Geographical separation of K and W call signs

Following a practice inaugurated in 1912 when the federal government first licensed radio stations, beginning in 1921 broadcasting stations have generally been assigned call signs beginning with "K" when their
community of license In American, Canadian, and Mexican broadcasting, a city of license or community of license is the community that a radio station or television station is officially licensed to serve by that country's broadcast regulator. In North American broad ...
is located in the west, and with "W" in the east. (The FCC proposed ending this policy in 1987, in order to allow unrestricted assignments of K and W stations throughout the country. However, it was decided to retain the rule due to industry objections.)"In the Matter of Amendment of Part 73 Relating to Call Sign Assignments for Broadcast Stations"
MM Docket No. 87-11, Adopted: October 20, 1987 (FCC.gov)
The original boundary line ran northward from the Texas-New Mexico border. In early 1923 the boundary was moved to its present location of the Mississippi River, in order to better balance the populations in the two regions. The geographical separation of "K" and "W" prefixes applies only to radio and television broadcasting stations, and is not followed for
weather radio A weather radio is a specialized radio receiver that is designed to receive a public broadcast service, typically from government-owned radio stations, dedicated to broadcasting weather forecasts and reports on a continual basis, with the routine w ...
,
highway advisory radio A travelers' information station (TIS), also called highway advisory radio (HAR) by the United States Department of Transportation, is a licensed low-powered non-commercial radio station, used to broadcast information to the general public, inclu ...
, or
time signal A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day. Church bells or voices announcing hours of prayer gave way to automatically operated chimes on public clocks; however, a ...
stations; nor does it apply to auxiliary licenses held by broadcast stations, such as
studio-transmitter link A studio transmitter link (or STL) sends a radio station's or television station's audio and video from the broadcast studio or origination facility to a radio transmitter, television transmitter or uplink facility in another location. This is ...
s and inter-city relay stations. For stations located in U.S. possessions, Puerto Rico and the U.S. Virgin Islands are considered to be east of the Mississippi River, and all their stations have been given standard "W" call signs. The Pacific Ocean territories of Guam, the Northern Mariana Islands, and American Samoa are considered to be in western "K" territory, although assignments here have been less consistent. Currently all but one of these stations have "K" calls; the exception is
WVUV-FM WVUV-FM (103.1 FM, "V103") is a radio station licensed to serve the community of Fagaitua, American Samoa. The station is located on the second floor of the Aitulagi Building office complex in Tafuna, along with sister-stations KKHJ-FM and KK ...
in Fagaitua, American Samoa, which received its call while it was paired with a since-deleted AM station, WVUV. The 1923 boundary shift meant that a number of existing stations with "W" call letters were located in a section of country that was now being issued "K" call letters, but these earlier stations were allowed to keep their now non-standard call signs. Examples of these stations include WBAP (Fort Worth, Texas), and
WDAF-FM WDAF-FM (106.5 MHz) is a commercial radio station licensed to Liberty, Missouri, and serving the Kansas City metropolitan area. Owned by Audacy, Inc., the station airs a country music radio format, branded as "106-5 The Wolf." Studios and off ...
and
WDAF-TV WDAF-TV (channel 4) is a television station in Kansas City, Missouri, United States, affiliated with the Fox network. The station is owned by Nexstar Media Group, and maintains studios and transmitter facilities on Summit Street in the Signal H ...
(Kansas City, Missouri), which inherited their calls from the original WDAF (now KCSP). Although a long established convention, the K-W division has not always been rigidly followed, and over the years a few exceptions have accumulated. One prominent example is KDKA in Pittsburgh, Pennsylvania, which was licensed in 1920 during a short period when new land stations were issued call signs from a block of letters that previously had been reserved for ship stations. The FCC has also been lenient in the case of relocations that result in a station moving to the other side of the boundary, especially when close to the Mississippi River. The most extreme example occurred in 2013, when television station KJWP was allowed to keep its call letters even after moving from Jackson, Wyoming to Wilmington, Delaware; the station changed its call letters to
WDPN-TV WDPN-TV (channel 2) is a television station licensed to Wilmington, Delaware, United States, serving the Philadelphia area as an affiliate of the classic television network MeTV. It is owned by Maranatha Broadcasting Company alongside Allentown, ...
in 2018.


Three-letter call signs

Starting in 1921, most broadcasting stations were assigned three-letter call signs. However, within a few years there would be hundreds of stations, and there were not enough three-letter calls to go around, so beginning in April and May 1922 most new broadcasting stations were instead issued four-letter calls. Over the next few years a small number of additional three-letter calls were authorized, with the final grant made in 1930 to WIS in Columbia, South Carolina. In the past, base three-letter calls could only be shared by stations located in the same community and under common ownership. A prominent dispute involving this issue occurred in the 1980s, when it required several petitions before a station in Granite City, Illinois, was permitted change its call letters to KWK-FM (now
WARH WARH (106.5 MHz "106.5 The Arch") is a commercial FM radio station licensed to Granite City, Illinois and serving Greater St. Louis including sections of Illinois and Missouri. WARH is owned by Hubbard Broadcasting and airs an Adult Hits rad ...
), matching its sister station, KWK (now
KXFN KXFN (1380 AM broadcasting, AM) is a radio station in St. Louis, St. Louis, Missouri. It is owned by Relevant Radio, Relevant Radio, Inc. and airs an English language Christian radio, Catholic radio format, format. The station has a colorful hist ...
) in St. Louis, Missouri. In addition, beginning in the mid-1980s stations which were previously co-owned but later separated no longer are required to have one of the stations give up the three-letter call, which is why WWL and
WWL-TV WWL-TV (channel 4) is a television station in New Orleans, Louisiana, United States, affiliated with CBS. It is owned by Tegna Inc. alongside Slidell-licensed MyNetworkTV affiliate WUPL (channel 54). Both stations share studios on Rampart St ...
in New Orleans can still share the assignment. Under current FCC regulations in force since 1998, the limits on reassigning three-letter call signs have been relaxed. The restriction requiring a common community of license was removed, and an owner of a station with a three-letter base call sign can now request the same three-letter call (with an "-FM", "-TV", or "-LP" suffix as necessary) for any station under common ownership. CBS Radio most prominently took advantage of this rule: resurrecting WJZ and adding
WJZ-FM WJZ-FM (105.7 MHz) is a commercial radio station licensed to Catonsville, Maryland, and serving the Baltimore metropolitan area. The station is owned by Audacy, Inc. through licensee Audacy License, LLC, and it broadcasts a sports radio for ...
in
Baltimore Baltimore ( , locally: or ) is the List of municipalities in Maryland, most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic (United States), Mid-Atlantic, and List of United States cities by popula ...
, as well as
WBZ-FM WBZ-FM (98.5 FM) is a commercial sports radio station licensed to Boston, Massachusetts, serving Greater Boston and much of surrounding New England. Owned by the Beasley Broadcast Group, WBZ-FM is the Boston affiliate for Fox Sports Radio; t ...
in
Boston Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...
. In most cases the FCC will not reissue a three-letter call sign after all the stations that had been using it switch to four-letter calls, but there have been a few exceptions where a station has been permitted to reclaim an "abandoned" three-letter call. This happened most recently in 2000, when KKHJ in Los Angeles was allowed to change back to KHJ, fourteen years after it had last used the three-letter call. The justification that the FCC accepted was that the first two letters of "KKHJ" are pronounced "caca" in Spanish, which was considered offensive."Mystique of the Three-Letter Callsigns"
by Thomas H. White (earlyradiohistory.us)


Suffixes

As the number of broadcasting stations has increased, the FCC has adopted a number of suffixes for use by FM and TV stations to allow multiple stations to share the same "base" three- or four-letter call sign. (AM and shortwave stations have never had "-AM" or "-SW" or any other suffixes.) For example, in addition to an FM station with the call letters WFOX, there are also WFOX-TV and a low-power FM station, WFOX-LP. And in addition to shortwave station KSDA, there is also a KSDA-FM. Suffixes are optional for full power FM and TV stations, unless another station shares the same three- or four-letter base call sign, requiring a differentiation between the two stations. Reviewed below are the various broadcasting station suffixes: * FM: The FM radio band was established on January 1, 1941, and from the beginning educational stations received standard unique four-letter call signs. Commercial stations within the original FM band were assigned transmitting frequencies that spanned from 43.1 MHz to 49.9 MHz, and the FCC initially issued these stations standardized call signs that included the last two digits of their frequency plus a common closing letter or letters that indicated their community. This resulted in call signs that were hard for the public to differentiate, for example, as of February 1942 there were nine commercial New York City stations operating on frequencies ranging from 43.1 to 47.5, which were assigned call signs between W31NY and W75NY. In order to eliminate this confusion, the FCC announced that, effective November 1, 1943, the 45 existing commercial FM stations would change to standard call letters. At the same time, the "-FM" suffix was introduced, which meant that FM stations could use the same base call letters as an existing AM station if they added "-FM" to their call. One restriction was that the paired stations had to have common ownership and be located in the same community. * TV and DT: Commercial television was introduced in the United States in July 1941, and initially TV stations were assigned standard unique four-letter call signs. In August 1946 the "-TV" suffix was introduced, which, like "-FM", included the restriction that paired stations had to have the same owners and be located in the same community. The "-DT" suffix was introduced as part of the later conversion of TV stations from analog to digital transmissions. During a transition period, digital TV stations were identified using -DT suffixed calls, with the base call staying the same as the one assigned to their analog sister station, e.g., WRC-DT was paired with WRC-TV, etc. With the termination of the analog stations in June 2009, most digital TV stations inherited the calls formerly used by their analog counterparts. However, the FCC provided that these stations could optionally keep their -DT suffix, and a relative few elected to do so. * LP: Beginning in 1995, the FCC allowed analog Low Power TV stations to be issued four-letter calls with an "–LP" suffix, although this station classification was largely eliminated with the conversion to mandatory digital TV as of July 14, 2021."FCC Public Notice: Media Bureau Reminds Low Power Television and Television Translator Stations That the July 13, 2021, Digital Transition Date and Other Important Deadlines Are One Week Away"
(DA 21-786), July 6, 2021 (FCC.gov)
In 2001
Low Power FM Low-power broadcasting is broadcasting by a broadcast station at a low transmitter power output to a smaller service area than "full power" stations within the same region. It is often distinguished from "micropower broadcasting" (more commonly ...
stations were also allowed to request -LP suffixed call letters. * CA, LD, CD and D: In 2000 a new Low Power analog TV classification of
Class A television The class A television service is a system for regulating some low-power television (LPTV) stations in the United States. Class A stations are denoted by the broadcast callsign suffix "-CA" (analog) or "-CD" (digital), although very many analog - ...
stations was added, with these stations eligible to receive standard call letters with a "-CA" suffix, although this classification was also largely eliminated with the July 14, 2021 termination of analog TV stations. After the introduction of digital TV, an "-LD" suffix was made available for standard Low Power digital TV stations, with digital Class A TV stations eligible for a "-CD" suffix. Low power digital TV stations, including translators, that still have alphanumeric call signs based on their channel number receive a "–D" suffix, as in W08EG-D. The FCC makes no differentiation between translating and originating LPTV stations, thus either type of station could have an alphanumeric or a regular "-LP" or "-LD" call sign. * FM Boosters: "Boosters" extend a station's coverage by transmitting on the same channel as an originating station. FM boosters receive call signs which repeat the entire call sign of the primary station, plus a sequential numeric suffix, like "FM1". Only LPFM boosters have multiple suffixes. The longest possible call sign in the United States (nine characters) went into use for the first time July 22, 2017, when
KWSV-LP KWSV-LP (99.1 FM, "99.1 The Ranch") is a low-power FM radio station licensed to and serving Simi Valley, California. The station is owned by Strategic Communications Group and broadcasts a country music format from its studios located inside Simi ...
signed on booster KWSV-LP-FM1.


FM and TV translator stations

Translators Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. The English language draws a terminological distinction (which does not exist in every language) between ''transl ...
are low-powered transmitters that rebroadcast an originating station's programming on a different channel or frequency. The naming convention for FM translators includes their three-digit FM channel number (from 200 to 300), followed by two sequentially assigned letters – for example,
K237FR K237FR ("Olympia's 95.3 KGY") is a translator radio station licensed to Tumwater, Washington, which serves the Olympia, Washington region. It broadcasts with 220 watts at 95.3 FM, relaying the classic hits programming carried over the HD2 subchan ...
. The translator may identify itself hourly by voice or Morse code. The primary station may instead choose to identify all its translators together; if it does so, the identification must occur once between 7 a.m. and 9 a.m., once between 12:55 p.m. and 1:05 p.m., and once between 4 p.m. and 6 p.m. local time. The policy for TV translators consists of a leading geographical letter K or W, followed by the two-digit channel number on which they operate (02-83), and closing with two sequentially assigned letters; for example, W04AX. In 2009, the FCC began allowing digital television stations to apply for "digital replacement" translator stations, which are not given a separate call sign, instead taking on the one of the primary station. This is only in the case of areas that would lose coverage due to the digital television transition. , channels 7, 9, and 13 in the western United States are up to K07Z''x'', K09Z''x'', and K13Z''x'', respectively. In the digital era, these call signs continue in use with an optional -D suffix to indicate digital operation. The FCC has since extended K-prefixed translator call signs on channels 7 and 13 to three-letter suffixes; what is now
KMNF-LD KMNF-LD (channel 7) is a low-power television station in Mankato, Minnesota, United States, affiliated with NBC and The CW Plus. It is owned by Gray Television alongside dual CBS/Fox affiliate KEYC-TV (channel 12). Both stations share studios ...
operated briefly under the six-character call sign K13AAR-D in 2018, and was later granted a channel 7 construction permit with call sign K07AAH-D before changing to its current sign.


Non-broadcast stations


Amateur stations

United States amateur radio call signs consist of one or two letters, followed by a single digit, and closing with one to three more letters. The number in the call sign indicates in which of the ten U.S. radio districts the license was issued. (It is no longer necessary for U.S. amateur radio operators to change their call signs after moving into a new district.) Most amateurs going to an exotic location will add a "/location" suffix to show their current operating site, for example, a station visiting American Samoa might sign "(regular call sign)/KH8". American amateurs are permitted to operate in Canada under their own call signs with a location indicator. Outlying areas have special calls. For example, those issued in Hawaii can (like other American call signs) start with "A", "K", "N", or "W", but then will have "H6" or "H7" before the one to three additional letters. Other Pacific possessions use other "H" numbers. For example, a station on Guam could be "KH0–". Stations in Alaska have "L" as their second prefix letter, and stations in the Caribbean region (such as Puerto Rico and the U.S. Virgin Islands) use "P" for their second letter. Generally the shorter the call (up to a 1x2 or 2x1 format) the higher the grade of license, but amateurs who upgrade are not required to change their call signs. In any case some of the available blocks have been used up. The 1x1 call signs, such as K6O, are for short-term special event stations. Amateur stations are required to identify themselves by their call sign once every ten minutes during a communication and at the end of the communication.


Other services

* Experimental stations have alphanumeric call signs, with "X" as the first letter following a regional digit. (All television and most FM stations that were operational before World War II were licensed as experimental stations.) Notable experimental stations included Major Armstrong's FM station
W2XMN W2XMN was an experimental FM radio station located in Alpine, New Jersey. It was constructed beginning in 1936 by Edwin Howard Armstrong in order to promote his invention of wide-band FM broadcasting. W2XMN was the first FM station to begin regula ...
in Alpine, New Jersey;
Powel Crosley Jr. Powel Crosley Jr. (September 18, 1886 – March 28, 1961) was an American inventor, industrialist, and entrepreneur. He was also a pioneer in radio broadcasting, and owner of the Cincinnati Reds major league baseball team. In addition, Crosl ...
's 500kW superpower AM W8XO, operating at night carrying
WLW WLW (700 AM) is a commercial news/talk radio station licensed to Cincinnati, Ohio. Owned by iHeartMedia, WLW is a clear-channel station, often identifying itself as The Big One. WLW operates with around the clock. Its daytime signal provides ...
's programming; and Don Lee's pioneering television station, W6XAO in Los Angeles. Synchronous AM station "booster" transmitters receive experimental call signs which incorporate the primary stations' call letters in their call signs, for example, WA2XPA was paired with WAPA, and WI2XAC was paired with WIAC. *
Time signal A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day. Church bells or voices announcing hours of prayer gave way to automatically operated chimes on public clocks; however, a ...
and standard-frequency stations have the reserved call signs WWV, WWVB through WWVI, WWVL, and WWVS. This grouping is derived from shortwave station WWV of Fort Collins, Colorado, which was the U.S. government's first such station.
WWVB WWVB is a time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST). Most radio-controlled clocks in North America use WWVB's transmissions to set the correct time. The 70 ...
and
WWVH WWVH is the callsign of the U.S. National Institute of Standards and Technology's shortwave radio time signal station located at the Barking Sands Missile Range, in Kekaha, on the island of Kauai in the state of Hawaii. WWVH is the Pacific si ...
are also currently in use, while WWVL was active from 1962 through 1972. Standard broadcasters may use these call signs with a suffix; what is now
WVBX WVBX (99.3 FM "Live 99.3") is a commercial radio station licensed to Spotsylvania, Virginia and serving the Metro Fredericksburg area. WVBX is owned and operated by Alpha Media LLC, through licensee Alpha Media Licensee LLC. It airs a contemp ...
operated as WWVB-FM from 2008 through 2009. *
NOAA Weather Radio NOAA Weather Radio NWR; also known as NOAA Weather Radio All Hazards is an automated 24-hour network of VHF FM weather radio stations in the United States (U.S.) that broadcast weather information directly from a nearby National Weather Servi ...
stations operating between 162.4 and 162.55 MHz have call signs consisting of a "K" or "W" followed by letters, and two digits. The "K" and "W" prefixes are used on both sides of the Mississippi River (for example, KHB36 in Washington, D.C. and WXK25 in El Paso, Texas). *
Highway advisory radio A travelers' information station (TIS), also called highway advisory radio (HAR) by the United States Department of Transportation, is a licensed low-powered non-commercial radio station, used to broadcast information to the general public, inclu ...
stations operating on the AM band have call signs consisting of "K" and "W" followed by two or three letters and three digits. As with weather radio, "K" and "W" calls are assigned on both sides of the Mississippi River. * Leisure craft boats with VHF radios do not have to be assigned call signs, in which case the name of the vessel is used instead. Ships wishing to have a radio license anyway are under FCC class SA: "Ship recreational or voluntarily equipped." Those calls follow the land mobile format of the initial letter K or W followed by one or two letters, followed by three or four numbers (such as KX0983 or WXX0029). * Military call sign systems: ** AAA–AEZ and ALA–ALZ are reserved for Department of the Army stations. ** AFA–AKZ are assigned to the Department of the Air Force. ** NAA–NZZ is jointly assigned to the Department of the Navy and the U.S. Coast Guard Call signs in the western United States can be confused with International Civil Aviation Organization (ICAO) airport codes, because they are four-character codes beginning with "K". Examples include KSFO ( San Francisco International Airport and radio station
KSFO KSFO (560 AM) is a commercial radio station in San Francisco, California. It is owned by Cumulus Media and airs a talk radio format. The station's studios and offices are on Battery Street in the SoMa district of San Francisco, along with f ...
), KLAX ( Los Angeles International Airport and
KLAX-FM KLAX-FM (97.9 FM) is an American commercial radio station located in East Los Angeles, California, broadcasting to the Greater Los Angeles area. KLAX-FM airs a regional Mexican music format branded as "La Raza". The station has studios in Los ...
), and KDFW (
Dallas/Fort Worth International Airport Dallas/Fort Worth International Airport , also known as DFW Airport, is the primary international airport serving the Dallas–Fort Worth metroplex and the North Texas Region in the U.S. state of Texas. It is the largest hub for American Ai ...
and
KDFW KDFW (channel 4) is a television station licensed to Dallas, Texas, United States, broadcasting the Fox network to the Dallas–Fort Worth metroplex. It is owned and operated by the network's Fox Television Stations division alongside MyNe ...
(TV)).


Historical overview


Early history

The use of call letters predates the invention of radio, and were introduced as part of landline
telegraph Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas p ...
communication. Telegraph operators generally used Morse code, and it was standard practice to assign identifying letters to individual offices located along a line. Early radio stations (originally called "wireless telegraphy") commonly employed former telegraph operators, who continued the practice. While there was no need for telegraph stations to coordinate their assignments, the great distance that radio signals traveled required international standardization. As early as 1906, the Service Regulations adopted by the Berlin International Wireless Telegraph Convention specified that "calls shall be distinguishable from one another and each must be formed of a group of three letters". Despite this pronouncement, the United States would be slow to adopt this standard, largely because radio stations were unregulated at this time. Individual stations selected their own call signs, commonly only one or two letters, with little concern about duplication. The first U.S. organization to conform to the international standard was the U.S. Navy, which in 1909 switched from two-letter calls scattered throughout the alphabet to three-letter calls, all starting with the letter "N". The lack of coordination and duplication of call signs used by merchant ships was eventually determined to be a threat to maritime navigation. A November 1911 report by Commissioner of Navigation Eugene Tyler Chamberlain"Call Letters"
''Annual Report of the Commissioner of Navigation to the Secretary of Commerce and Labor for the Fiscal Year Ended June 30, 1911'', submitted November 18, 1911 from Commissioner Eugene Tyler Chamberlain to Secretary Charles Nagel, page 52-53.
noted the lack of standards in the latest compilation of ship call letters, and decided to take measures to rectify the situation, invoking his authority given "by the act of July 5, 1884" to assign "signal letters to American merchant vessels". (Previously this had applied to four-letter signal flag identifiers). The new merchant ship radio call letters went into effect on June 30, 1912. Ships were divided into two geographical groups, with three-letter calls starting with "K" assigned to ships on the "Atlantic and Gulf Coasts", and calls starting with "W" assigned to the "Pacific Coast" vessels. No reason was given for splitting the ships into two groups, and this differed from the practice followed for the assignment of the earlier flag signal letters, which had been sequentially issued with no differentiation between the two regions. Nor was any explanation given why the letters "K" and "W" were chosen.


Radio Act of 1912

The United States did not license radio stations until the adoption of the
Radio Act of 1912 The Radio Act of 1912, formally known as "An Act to Regulate Radio Communication" (), is a United States federal law which was the first legislation to require licenses for radio stations. It was enacted before the introduction of broadcasting to ...
. This new statute placed the licensing authority, including issuing call letters to both ship and land stations, under the control of the Bureau of Navigation in the Department of Commerce. At this time the United States also started to participate with international regulations, and one of the first acts was to be formally assigned call letter blocks. The initial assignment allocated all call signs starting with "N" and "W", plus the range KDA-KZZ, for use by the United States.''Radio Call Letters''
Department of Commerce, May 9, 1913 (FCC.gov)
(Initially KAA-KCZ were assigned to Germany, but in 1929 this call letter block was transferred to the United States. AAA-ALZ were added after World War II.) The policy that had been adopted for ship stations assignments was "W call letters in the west, and K call letters in the east". For land stations, the reverse was now implemented, with western land stations getting K calls, and eastern stations receiving W calls. This policy is still followed for broadcasting stations assignments. During a short period, land stations were being issued call letters from a sequential block of "K" call letters that had previously been assigned only to ship stations. "K", "N", and "W" call letters were considered to be international assignments. Initially there were some classes of radio stations which did not qualify for these calls because they were considered to be only of domestic interest. This included the standard amateur radio stations, plus the three classes of "Special Land" stations: Experimental, Technical and Training School, and Special Amateur. The United States was divided into nine "Radio Inspection" districts, and amateur and Special Land stations were issued call signs that started with the district number in which they were located, followed by two letters. The first letter for standard amateur stations came from the range A-W. For Experimental stations, the first letter was "X", a practice that is still followed. "Y" was reserved for Technical and Training School stations, and "Z" for Special Amateurs. More letters were added as the number of stations grew. Effective October 1, 1928, the amateur and Special Land stations were "internationalized", with stations adding an initial "W" (for continental) or "K" (for territorial) ahead of their call signs' district number. In later years a greater variety of amateur call signs would be added.


Early radio broadcasting stations

The original radio stations were primarily used for private point-to-point communication. The early 1920s saw the introduction of radio broadcasting, and by the end of 1922 there were over 500 broadcasting stations operating in the United States. Most of the first broadcasting stations received randomly assigned three-letter call signs. However, in early 1922, due to the prospect of all the available three-letter call signs being used up, the government switched to four-letter calls that were sequentially assigned. Initially two different patterns were employed. In the east, beginning in April 1922 calls were issued in alphabetical order with "A" fixed as the third letter, i.e. WAAB, WAAC, WAAD... WBAB, WBAC... etc. Surviving stations from this era include WBAP (Fort Worth, Texas), WHAS (Louisville, Kentucky) and
WTAM WTAM (1100 AM) is a commercial radio station licensed to Cleveland, Ohio, and carries a news/ talk/sports format commonly known as "Newsradio WTAM 1100". Owned by iHeartMedia, WTAM serves Greater Cleveland and much of surrounding Northeast Oh ...
(Cleveland). In April 1923 the pattern switched to calls centered on "B", including WBBM (Chicago),
WCBM WCBM (680 kHz) is a commercial AM radio station in Baltimore, Maryland. It is owned by WCBM Maryland, Inc., and broadcasts a talk radio format, calling itself "Talk Radio 680 WCBM." The radio studios and offices are on York Road in Luthervi ...
(Baltimore) and WMBD (Peoria, Illinois). In the west, after a small number of KD—four-letter calls were issued, the government switched to KF--, KG—and KI—calls issued in alphabetical order, including
KFQD KFQD (750 kHz) is a commercial AM radio station in Anchorage, Alaska known as "News Talk 750 and 103.7 KFQD." It broadcasts a News/Talk radio format and is owned by Alpha Media LLC. The studios and offices are on Arctic Slope Avenue in Anchora ...
(Anchorage, Alaska), KGFX (Kalispell, Montana) and KIUL (Garden City, Kansas). Beginning in the mid-1920s it became the norm for station owners to request call letters of their own choosing. However, in cases where no preference has been stated, the government will make its own assignment.


1983 deregulation

In late 1983, the FCC adopted a number of changes that greatly reduced its role in call letter assignments and disputes, including:"In re Matter of: Revision of Section 73.3550 of the Commission's Rules with respect to the Assignment of New and Modified Call Letters to AM, FM and TV Broadcast Stations"
MM Docket No. 83-373, Adopted: December 1, 1983.
* Ended the ban on issuing call letters that are "not in good taste". The FCC noted that any objections could be handled by a complaint through the federal courts. * Eliminated the requirement that a station seeking to change its call letters had to notify local stations of the pending request. In addition, the FCC would no longer set aside a thirty-day period to receive objections and rule if the new calls met FCC standards, because call letter changes were now being authorized as soon as they were received. * Eliminated the requirement that stations with four-letter calls operating on different services had to be located in "the same or adjoining communities" in order to have the same base call. (The single-community restriction remains in force for three-letter calls). In 1987, the requirement was further relaxed, now allowing common four-letter base call signs to be issued to stations with different owners, although permission had to first be obtained from the current call letter holder. * Adopted a "first requester" policy for reassignment of relinquished call letters. The previous rule stated that after a call was relinquished, the reassignment would go to the senior broadcaster requesting during the next fifteen days. * Eliminated the rule that relinquished call letters could not be reassigned to the same community for 180 days. * Eliminated the requirement that "suitable clearance" had to be obtained in order to receive call letters that were the initials of a current or former president, or a government agency.


See also

* Amateur radio in the United States#Call signs *
Call sign In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a unique identifier for a transmitter station. A call sign can be formally assign ...
*
City of license In American, Canadian, and Mexican broadcasting, a city of license or community of license is the community that a radio station or television station is officially licensed to serve by that country's broadcast regulator. In North American br ...
– another element of station licensing * Facility ID – used by the FCC in the United States to distinguish broadcast stations without regard to call sign changes


External links

Call sign information for U.S. stations are set out in chapter I of the FCC rules, Title 47 (Telecommunication) of the Code of Federal Regulations (C.F.R.): * : General overview of call sign assignments, including a detailed summary of standards and practices for various license classes. * : Detailed information for broadcast stations.
Media Bureau Call Sign Actions
(Monthly U.S. Federal Communications Commission Public Notices)

(FCC Media Bureau Call Sign Desk)


References

{{Call signs
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
Communications in the United States Mass media in the United States