Man, the things I think of when I can't sleep! Or what pop in my head when I wake up! Hey, I could have a worse hobby than radio...fortunately, my wife tolerates my enthusiasm, until someone asks me a question, then she'll tell me, "Don't talk their head off!"
Ray Poindexter's book, "Arkansas Airwaves" is a fantastic source of answers to questions such as the above...but you have to read it to find the answers! I think I have that answer:
In late September of 1924, KFMQ had installed a new 500-watt transmitter. The frequency was changed to 1090 kilocycles (kilohertz to you young 'uns!) or 275 meters. So far, I haven't found a reference before that (pp. 52 in the book), and I'll keep digging. Does anyone else have a reference to an earlier usage of 1090 in Arkansas?
Only a few frequencies were allowed by the Department of Commerce for broadcasting; many radio stations had to share time and came to gentlemen's agreements as to when and when not to transmit, taking turns to crank out their broadcast fare. Seemingly, the frequency of choice I noticed most in this and other sources appear to be 833 kilocycles, or 360 meters. In or around the mid- 1920's, th DoC allowed the AM broadcast band to "open up" from 550 to 1500 kilocycles...which I'm sure resulted in a much less-congested radio spectrum and allowed more broadcast time for stations. However, the years that followed show that the DoC, later the Federal Radio Commission, had stations hopscotching all over the band, changing frequencies so fast, you'd need a program to tell the players! But that's another story....
Reminds me of Abbot and Costello's "Who's On First?"
Bud S. (firstname.lastname@example.org)