When ethnic enclaves tend attract those of the same ethnicity vs. "pan-ethnic" groups
 

For example, Chinatowns attracting other East Asian immigrants not only the original Chinese who settled.

Or neighborhoods that have not only native-born African Americans but Jamaican or other Afro-Caribbean and African immigrants.

Or how in some cases Persian neighborhoods like those in LA have Persian Jews and non-Jewish Persians living side by side, but in other cases Persian Jews live in Jewish neighborhoods, not among non-Jewish Persians.

Sometimes religious groupings can unite a demographic in an area (eg. Muslims of African-American, Middle Eastern and immigrant backgrounds, religious Jews of more than one origin), other times it's language (Spanish speakers of various Latin American backgrounds, Portuguese and Brazilians together) but other times it seems like it might be race (eg. African American and African immigrants living side by side in say, DC or Atlanta).

What determines the choices made by people of pan-ethnic groupings in some cities versus others? Do cities with a longer history of racial segregation have race-based enclaves more, and cities with newer immigrants clustering more by cultural group? Are some kinds of clustering together more common in some cities/regions etc than others?

some american inner suburbs sort of “market” themselves as “pan-ethnic” enclaves i’ve noticed.

Seattle's International District.

A lot of Chinatowns seem to turn into pan- (east and southeast, not sure about south Asians) Asian immigrant enclaves (eg. Seattle's International District, Cleveland's Asiatown) after a while.

Other times, ethnic enclaves like Little Portugal or Portuguese neighborhoods benefit from the shared presence of Brazilian/Latin American demographics that are culturally/linguistically similar.

But in other cases, ethnic neighborhoods just get assimilated away or switch hands to another demographic that's not necessarily culturally related (eg. what happens to many Little Italy's in many cities). With Little Italy and Greektowns in many cases, it seems like it's mainly just the Italians and the Greeks, and without them, the enclaves just assimilate away with no culturally similar "successor" the way Chinatowns can retain cultural continuity with say, Vietnamese immigrants who follow after some number of the Chinese leave, or Portuguese neighborhoods can retain cultural continuity with later Brazilian immigrants.

It's interesting that in some cities lots of ethnic groups that would not have seen one another as similar back in the old country share an enclave (eg. Cleveland's Asians in the former Chinatown), yet in another place like New York City's metro area Chinatowns it's totally not the case and even the same ethnic group subdivides its enclaves (eg. Flushing, Queens vs. the old Manhattan one) having different kinds of Chinese immigrants who don't necessarily find cultural common grounds with one another.

The NYC area's Little Portugals have transitioned to Little Brazils. Ironbound in Newark is the most obvious example.

NYC area Chinatowns have probably become less diverse over time. Flushing was more pan-Asian 20 years ago. Now it's dominated by Chinese/Taiwanese. Koreans have moved somewhat East and South Asians have moved somewhat South.

Houston's (newer) Chinatown is now mostly Vietnamese.

Miami's "Little Havana" is now largely populated by non-Cuban spanish speaking immigrants.

The Little Egypt (also referred to as Little Morocco) area of Astoria, Queens seems to be attracting a rapidly growing and broader Islamic population. I'm about 20 blocks west from the heart of it on Steinway Street and have noticed a big uptick in the number of Muslims in my part of Astoria. They even shut down a major street for Eid Al-Fitr.