Phil,
I am an American and I live in Southern California (that will be relevant at the end).
To the ear, no. Most Americans would probably not make this mistake. Seeing these two places in written form, however, yes, many Americans would (regretably) make this mistake. I must preface that by saying that, in Southern California at least, there is largely a paradoxical celebration of diversity that goes hand-in-hand with complete ignorance of the roots of that diversity. It's a culture made of veneer.