Most likely that that's just the way the FCC licensing process assigned them at the various times the transmitters were established, more or less at random within the FCC rules applicable.
The initial letter is a US geographic division, "K" for west of the Mississippi River, "W" for those east (with a few very old stations west having a "W"). The 2-3 digits alphanum just being this general transmitter class (like microwave P-P links also have).
You might find something on the fcc.gov website, but that is the most convoluted place on the internet, you may never be seen again after entering it
. It drove me around the bend
getting my licenses (and the site is considerably improved/automated from before).
