What does music flow at KNX 50 years ago have to do with currents at KROQ? Nothing.
If we are tracing a timeline of how stations imaged, we can go back as far as we want.
I was looking at a promotional booklet for a network affiliate in Minneapolis which was published in 1935. The station spent lots of money on a 20-page booklet with photos of all the local and web talent, its building and transmitter, the office staff and the engineers and some local city shots to tie it together. The call letters were on every page, often many times. But nowhere did it mention the station's frequency.
Back in '35, it was not needed to give the dial position. The station's image was based, mostly on the network and key local shows. So that is what they promoted. That was their image.
As we moved from network radio to music formats, imaging changed. On air presentation was different, and stations got names instead of just letters. We got jingles and sounders and stingers. That was imaging then.
Today, the imaging is not to build station importance, but to create longer listening incidents and more return visits. But it is still imaging.
In the 30's and 40's, ratings showed hours and half hours, not daypparts. Now we look at dayparts, but analyze by the minute. How we do imaging changes and what we define as imaging does too. But it is just a progression, not something new.