Yeah about same, I remember reading one of those old scanner frequency list sites that are gone now 12 years ago after moving here that said something about how they used to use almost similar to how CHP does back then.
Yeah El Paso Natural Gas and BNSF are the last ones I've confirmed active, I was able to kerchunk the El Paso repeater in my area this morning just to see if it was still alive. And then BNSF has 44.58 everywhere and you can see the tall vertical on a alot of their self supported towers with the microwave antennas. The tower generally only receives most of the time and the locomotives transmit telemetry from those long white radomes on the top of the cab that kind of look like ice skates. I saw one with the radomes removed last week and it was just a vertical bent parallel to the roof. I can receive them from pretty far away though over mountains.
It’s from 1948 in this magazine, on file page 41: https://www.worldradiohistory.com/Archive-FM-Magazine/FM-1948-07.pdf
As I remember, 39.18 was the statewide low band frequency that was for agencies to talk to each other which is now called interop. I can tell you quite a while back, (now that I think about it that was 30+ years ago) most sheriff's offices and a few cities monitored it all the time. You could use that frequency when traveling out of your jurisdiction if your vehicle had a low band radio. MCSO Lake Patrol had it in most because of their Lake Patrol Dive Team in the day. I doubt many even have radios for it anymore.
