Well, Chicago basically held sway over most of the families west of the Mississippi. Same as NYC held sway over a lot of the East Coast families. I don't think it was ever officially laid down that way, it's just that the western families knew that Chicago had the most muscle and the most cash so if they wanted to send somebody to oversee some rackets in California it was more like "We're not asking you, we're telling you."

I don't know a whole lot about the Cali families themselves. All of them are virtually non-existent except for a couple of old-timers still kicking around. Maybe read Jimmy Fratianno's book, he was a rat from the L.A. family.