Well, I'm from Texas. We have the same problems that other border states do. And we have a large and growing Hispanic population. But we are now as solidly GOP as California is Rat-infested. That's because Hispanics here vote GOP in increasing numbers. It's happening here and in many other states, but not in California. So why isn't it happening in California?
I think it's the typical red/blue effect -- the large population centers everywhere voted Democrat, and likely for the same reason: Democrats of all stripes tend to congregate there. California has been a magnet for lefties for a long time -- its legislature has been solidly Democrat-controlled for decades, so perhaps a better question might be: why did California continue to support Republicans until 1992?