Marie, your phrasing is just fine...no worries!  I'll try to weigh in on your question the best that I can, although it won't be from the perspective of a person who lives in the Bay Area since I'm from Southern Cali. 

I actually had this same question about cheer several years ago before my daughter became involved in competitive cheer.  The gym we belong to now is very well diversified.  At one time I don't believe all-star cheer was very culturally diverse, but the sport is slowly evolving into one that is enjoyed by a variety of girls and guys from so as many different ethnic  and cultural backgrounds. 

There are a few driving forces that dictate the make up of cheer gyms like location of the facility, economic status of the community, as well as the ethic/cultural makeup of the community.   A person with a background in all-star cheer is not likely to open a gym in an area where there is no interest whether due to lack of exposure to the sport of competitive cheer or due to greater interests in other sports dictated by the history and cultural background of the area.  Keep in mind that competitive cheer is also very expensive and the general belief for years had been that competitive cheer was reserved only for those who could afford it.  Struggling financially to pay for such a thing was out of the question.  Some may disagree, but I speak from the perspecive of one whose parents absolutely believed such things (I'm probably older than you but not so old that competitive cheer wasn't around during my childhood...lol).  Now that I'm older and wiser (to this game especially) I realize that this sport has always been open to anyone of interest and can be enjoyed by anyone who's parents are willing do a few extra things to pay the required fees, if money is indeed a questionable thing.  Many parents saw no sense in paying so much for an extracurricular activity. But now the interest in the sport has grown so quickly and its interest spans to so many different ethnic groups and cultural backgrounds that its growing in leaps and bounds. It's well worth the MONEY it costs (cost of a small used car on a yearly basis), time spend (lots of it), and energy that kids and parents put into it (we're all on burn out mode right now but we love it).  Just think about Worlds!  There are people from other countries who are flocking to this sport who take it very seriously!  They travel to the United States to compete! WOW - that's just AMAZING! Who would ever have thought it would have taken off like this?  This sport is loved by all kids of all kinds and hopefully its interest will continue to spread to areas that have not had the pleasure of exposure yet.  When it does - they're in for a real treat! 

Ok, I rambled a lot here but I thought your question was very good and I had tons of info based on personal experiences to share.  I hope that I've answered your question without making it too heavy.  Check out some of the larger competitions or even you-tube performances when you get a chance.  Pariticipation is not yet equally distributed but for those groups that are not already well represented I expect that their numbers will continue to rise over the seasons to come. Thanks for supporting competitive cheer and spread the word.