I worked at the Grand Canyon one summer in my BA degree years. By the end of the summer, I could tell every state; L.A. from San Francisco from San Diego, Denver, Dallas etc. And many European cities and some regions in some big cities. Couldn’t do it now. I am sure accents have changed in the 50 years since. It was fascinating, though. Many people don’t detect the differences between Aussies & NZ folks’ accents.
I can still hear the difference between Philly and Pittsburgh. Wisconsin and Minnesota etc. LOL