Broadcast call signs

Broadcast call signs are call signs assigned as unique identifiers to radio stations and television stations. While broadcast radio stations will often brand themselves with plain-text names, identities such as "cool FM", "rock 105" or "the ABC network" are not globally unique. Another station in another city or country may (and often will) have a similar brand, and the name of a broadcast station for legal purposes is normally its internationally recognised ITU call sign. Some common conventions are followed around the world.

Broadcast stations in North America generally use call signs in the international series.

In the United States, the first letter generally is K for stations west of the Mississippi River (including Alaska, America Samoa, Guam, Hawaii, and Northern Mariana Islands) and W for those east of the Mississippi (including Puerto Rico and the Virgin Islands); all new call signs have been 4-character for some decades, though there are historical 3-character call letters still in use today, such as KSL in Salt Lake City and WGN in Chicago.

There are a number of exceptions to the east/west rule, such as KDKA in Pittsburgh and WFAA in Dallas-Fort Worth, but these are historical artifacts from a rule change in the 1920s, and most of the exceptions are located in the states immediately to either side of the river, in the state of Louisiana in the metropolitan areas of Baton Rouge and Greater New Orleans, and markets north of the river's source such as Fargo-Moorhead and Duluth-Superior. The westernmost station in the continental United States beginning with W is WOAI in San Antonio. WVUV-LP in Pago Pago, American Samoa, was the westernmost station with a W call sign until 2008. KYW in Philadelphia (which originated in Chicago in 1921, moved to Philadelphia in 1934, and existed in Cleveland in the late 1950s/early 1960s) is now the easternmost station with a K call sign.

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