I know of firms that have professional trading and backed trading in San Diego, LA and San Francisco. Of course in this current market, which is tough for scalping, in order for one of these firms to back you you would probably have to have a profitable record. ( and if you have been profitable why would you need backing).
Nevertheless, I know of more than one firm in each of the above cites. One is my firm, in San Diego, and two of them are firms that were started by guys I used to trade with, (we all broke off from bright 4-6 years ago. One group has about 20 plus traders and one group has about 60 -70 when I last knew. If you are a serious trader I could give you the names of these other offices. And since I know rob tharp and he told me about this board I should mention he said was planning to open in an office in San Diego as well. So you see there is plenty of trading in Ca. In fact there was plenty of excellent trading in California as many of the guys I know had big years last year. (Since the spring it has been tougher).
However, the CA state tax does tick me off and sometimes Monday morning does seem to be a little early.