Wasn’t expecting a blanket putdown of Wikipedia. I guess YMMV.
I’ve lived in SoCal around 65 years and went to college in Riverside. I’ve always thought of the IE being more localized to the Riverside/San Bernardino area but, as the population density has ballooned east of LA, the IE seems to have expanded with it. Now it seems to go as far west as the Pomona area, but I don’t live there so I’ve never been that concerned with the specifics.
Oh, it does, greatly. The good is very good. The bad…oy! I mentioned that there are some entries where people are clearly knowledgeable, and have done their research. Unfortunately, I’ve run into more that were beyond awful. Some other areas where I am knowledgeable are some of the worst I’ve seen. And, I’m not referring to facts that are difficult to find or are ridiculously obscure, let alone very minor errors or simple typos. Those are forgivable and I don’t judge harshly on those. I’m referring to jaw-droppingly bad, serious errors from either poor - or no - research. And then there’s the Joker-esque style vandalism (for some reason I’ve run across that as false histories for some small California towns). Wikipedia is great as a quick reference, but always look deeper.