Jewish communities in US cities: size or age

This is a question for members of the Jewish community (of which I am a member) or others with insight on it: If you look at Jewish communities in American cities/metro areas today, which of these two variables is more important in determinng the vibrancy of the community, its ability to offer both the religious and (for lack of a better term) ethnic aspects of Jewish life: • the age of the Jewish community • the size of the Jewish community Let me explain. Cities like New York, Chicago, Philadelphia, and Boston have deeply rooted Jewish communities. Jews came in large numbers to such cities in the late 19th/early 20th century mainly from eastern Europe. Virtually all these immigrants were orthodox and the vast majority settled in heavily Jewish neighborhoods (paralleling other immigrant grops of the time like the Italians and the Poles). Jewish culture and religion flourished and Jewish institutions strongly served the needs of the people. In general, these cities have seen many Jews move to the south and west in the post-WWII years, dispering into cities across the nation. Yet these cities still retain a Jewish structure and traditon that newer Jewish communities may lack. Each has its own story of immigrant neighborhoods and how the community moved from one part of town to the other. Even today, many heavily Jewish neighborhoods can be identified. Eliminating perhaps two unique cities....Miami with its long history of Jewish resort and retirement as well as LA with its huge Jewish community that grew in the 20th century but is still pervassive (virtually all Jews, it seems, have relatives in LA....and some connection with Miami)...how does Jewish life differ in cities where the growth has come in more recent time, an era when Jews are more assimilated, less ethnic, often less strictly relgious, in less of a need for Jewish community services. I'm talking about places like Atlanta, Houston, Dallas, Phoenix, Las Vegas, among others. Each of these cities has a noteworthy Jewish community and the sizes of these communities may not be far removed from the traditional cities of the northeast/midwest (i.e. Cleveland, St. Louis, Pittsburgh, Baltimore, etc.); in fact, they may exceed these cities in Jewish population.But does their recent age, and the fact that the growth took place in this more assimilated era with its great degree of intermarriage make the newer communtiies appear "less Jewish" than older ones, even older ones with a smaller Jewish community, but one with strong community ties? NOTE: this discussion could apply to other ethnic communtiies as well but the American Jewish community, among the European immigrant groups may differ to the degree that being Jewish has both religious and ethnic overtones.>