LOL, those old "word" prefixes. We had POplar and DIamond.
at least in that era I knew exactly where anyone was by what their prefix was anywhere in L.A. or Orange County.
What really started to make thing dificult is when they started switching from manual relays to digital relays that took up about 10% of the space and numbers could be changed, hooked up, or disconnected with a simple computer entry.
They took entire areas, shut down the entire system for switch over and you got new numbers from a switching facility that had been converted already.
After they did that you couldn't keep track of where the numbers were.
It was about the same time that they broke up ATT and Pac Bell because we worked on every telephone company building ib L.A. putting in deviding walls so ATT employees couldn't get to Pac Bell employees, what a joke!