I probably have posted on this before. I may even be contradicting myself.
So who is the oldest radio station in America?
It's an opinionated debate of course; and the usual answer is KDKA-AM in Pittsburgh. But they are only the first commercially licensed station. There were hundreds of experimental radio stations that preceded them. As is typical, technology preceded legislative oversight. The right answer depends on just how you define "radio station."
1290 KUOA-AM is my current favorite vying nominee. An experimental wireless station was constructed at the University of Arkansas in 1897. Professor William Gladson performed this enterprising pioneer work a mere two years after Marconi began his work in Italy. As a result of this pioneer experimentation, the University of Arkansas constructed a wireless telegraph station that was subsequently granted the call sign 5YM.
After WWI University personnel turned their wireless endeavors into the direction of establishing a radio broadcasting station at the university. Thus it was that experimental became professional broadcasting in 1924 . The FCC granted them the calls KFMQ with 100 watts at 1140 kHz.
The call sign was changed to KUOA to better match the university name in 1926. Seven years later, U. of Arkansas sold the station. It changed hands, eventually ending up as the property of John Brown University in Siloam Springs where it remains today.
Most of my info on this is second hand, based on an article in Popular Communications, written apparently by Alice Brannigan. If she made this up, I apologize.