Why do radio stations begin with ‘K’ or ‘W’?

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Before there were TVs and streaming platforms, there was radio. It might not be the popular media source that it once was, but radios have done well to stand the test of time. It’s been more than a century since the first radio communication was made, but there’s a question that’s been plaguing us for a while now. Why do all these stations start with a “K” or “W”? It’s a widespread thing here in the States, and for the longest time, we weren’t sure why.

The call signs

This mystery stems from the days of the telegraph when call signs were used to identify operators. These signs (which were essentially letter sequences) were continued by radio operators as technology developed. They tended to favor ones that already existed, rather than create new combinations.

The repeated use of these signs created confusion, so in the 1910s the Bureau of Navigation decided to start using them for American ships. This is where the “K” and “W” first originated. Ships in the Great Lakes and the Pacific were identified with a “W,” while those in the Gulf of Mexico and the Atlantic used a “K.”

These specific labeling sequences remained in rotation when commercial radio stations started getting licensed. Although the Western side of the States used “W” and the Eastern side used “K” in regards to ships, their positions were reversed for radio stations. That meant that any commercial station east of the Mississippi River had a “K” affixed to them, while those on the other side had a “W”. The reason for the switch is still unknown.

Exceptions to the rule

Despite this rule being in place, not all radio stations abide by it. Some stations in the east still use a “W” and vice versa. The reason for this differs, with the main one being that the dividing line was not always located so neatly along the Mississippi River. Before 1923, it ran northwards from the Texas-New Mexico border. When the change was made, certain stations were advised to alter their call sign to relate to their location while others weren’t.

This is not the only reason why exceptions exist. Some radio stations were given a “K” because, for a brief period, the Bureau of Navigation decided that every new station was going to use that letter. This only lasted for around a year, but for the stations that formed during that time, the letter became a permanent addition.

Relocations and changes of ownership were the cause of other deviations, as well as a simple request from some stations to use a different letter. Stations like WTTW and KRAP did this, with the former choosing these letters to create an acronym. They see themselves as Chicago’s Window To The World.

Human error also came into play at times, although this was a rare occurrence.

The mystery is solved. If the presence of “K”s or “W”s on your favorite radio station has ever confused you, we hope this has made things clear.

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