Also, when I have lived in areas that were extremely homogeneous (where almost everyone was White and Protestant), the local culture had a greater tendency to give way to bland, corporate popular culture than areas that had a lot of different cultures living together. This is because in a culturally homogeneous area, the local culture is so taken for granted, it is quickly discarded in favor of the new. But where there is a variety of cultures all in the same place, everyone becomes more keenly aware of their own culture of origin, and they are much more likely to embrace it and preserve it. So I would say that mixing cultures in a particular geographic area is the best way to preserve the cultures of many localities.