Call signs in the United States
Call signs in the United States are identifiers assigned to radio and television stations, which are issued by the Federal Communications Commission and, in the case of most government stations, the National Telecommunications and Information Administration. 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 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. In the United States, the only time broadcasting stations are required to mention their call signs is during station identification 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 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, 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 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, 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.
- Owners: The major owned-and-operated stations of the Big Three television networks—ABC, CBS and NBC—have traditionally had call signs reflecting the network abbreviations. Stations operated by schools and universities commonly incorporate their school's initials, including WWVU-FM, and KUOM.
- Locations: Three stations have call signs that fully spell out their community of license: WACO-FM, WARE and WISE-FM. Other stations reference their community of license or designated market area with an abbreviation or initialism, such as WRAL-TV, WCSC-TV, WLOX, WSAV-TV, WPGH-TV, or WTSP.
- Numbers: Numerous television stations have chosen call letters that reference their channel number, either spelled out or using Roman numerals: WDIV-TV, WXII-TV, WXXV-TV, KXII, WIIC-TV , WPVI-TV, WIVB-TV, WTWO, KIXE-TV, and WXXI-TV. Some, like WGRZ and WDIO-DT, 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 in Seattle, which previously broadcast on 910 kHz ; and KIIS in Los Angeles, which originated on 1150 kHz.
Geographical separation of K and W call signs
The original boundary ran northward from the Texas–New Mexico border. In early 1923 the boundary was moved to its present location, the Mississippi River, in order to 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, highway advisory radio, and time signal stations, nor does it apply to auxiliary licenses held by broadcast stations, such as studio-transmitter links and inter-city relay stations.
For stations in U.S. possessions, too, the Mississippi River is the boundary. Puerto Rico and the U.S. Virgin Islands are east of the river, and all their stations have been given standard "W" call signs. The Pacific Ocean territories—Guam, the Northern Mariana Islands, and American Samoa—are in western, "K" territory, although assignments there have been less consistent. All but one of these stations have "K" calls; the exception is WVUV-FM in Fagaitua, American Samoa, which received its call while it was paired with a now defunct AM station, WVUV.
The 1923 boundary shift meant that a number of existing stations with "W" call letters were 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. These include WBAP, and WDAF-FM and WDAF-TV, which inherited their calls from the original WDAF.
Although a long established convention, the K–W division has not always been rigidly followed. One prominent exception 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 had been reserved for ship stations. Another is KYW, which was originally launched in Chicago by the Westinghouse corporation in 1921 and later moved to Philadelphia: the call sign was temporarily transferred to Cleveland, where it was used from 1956 to 1965.
The K-W division figured in another case that was ultimately decided in federal court. In 1979 the Commission denied a request to conform the call sign of WGNU-FM, licensed to Granite City, Illinois, with co-owned KWK, St. Louis, Missouri, to become "KWK-FM." The Commission said to issue a K call sign to a station licensed to a small community on the east bank of the Mississippi would confuse listeners as to the station's location, conforming it with a K call sign of a station licensed to a much larger community on the west river bank. The U.S. Court of Appeals for the District of Columbia Circuit disagreed and reversed the Commission, holding that granting conformances in the past in almost identical cases required the Commission to follow precedent and grant the "KWK-FM" conformance.
The FCC has also been lenient in the case of relocations that move a station to the other side of the boundary, especially when close to the Mississippi River, and in the two states that are divided by the river, Minnesota and Louisiana. The most extreme example occurred in 2013, when television station KJWP was allowed to keep its callsign even after moving from Jackson, Wyoming, to Wilmington, Delaware; the station changed its callsign to WDPN-TV in 2018.
In 2024, Tegna switched the call letters of KMPX, a television station in the Dallas–Fort Worth metroplex to KFAA-TV, which are similar to the calls of its sister television station, WFAA and providing complementary call sign branding for both stations in the same market.
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. Beginning in the mid-1980s stations which were previously co-owned but later separated no longer were required to have one of the stations give up the three-letter call, which is why WWL and WWL-TV 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 for any station under common ownership. CBS Radio most prominently took advantage of this rule to use the goodwill of those calls to launch sports radio sister stations on FM: resurrecting WJZ and adding WJZ-FM in Baltimore, as well as WBZ-FM in Boston.
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.