The demographics seem to be like that no matter what the hobby - especially if it applies to transportation of any sort. Being from GA and spending many years in TN, I was always involved in the street rod scene. Even though CA is known historically for hot rods and famous builders, the scene in the West is not nearly as active as the East Coast.
One of my hobbies for the past 16 years has been Pontiac Fieros. I was involved with setting up events back in GA and TN, and have done a run out here for the past 5. On the East Coast, we would have 50-60 cars show up from about 15 states. Since I have been doing my event in Central CA, we get between 25-30 cars a year and amazingly people in San Diego think the event is too far North (5 hour drive) while people in Sacramento think it is too far South (4 hour drive). In CA, people seem to love cars... just don't particularly enjoy driving them.