A lot are, but a lot aren’t. Jews actually pay for the upkeep of a long wire encircling much of Manhattan so that it counts as a place they’re allowed to do certain stuff on the sabbath

They’ve got their own police-like force across the river in wburg, and other places with high concentrations of orthodox jews

and even among jews that are culturally assimilated, they maintain a much tighter social network than, say, the american great grandchildren of swedish immigrants. there are like 3 million of those and 7 million american jews. having a distinct religion will do that. lutheran swedes and germans intermixed in the midwest quite easily