Bergen vs. Nassau vs. Westchester

[King of Kensington]

Of these three NYC suburban counties, which is the "odd man out"?

One obvious for Bergen being "different" is that it's in NJ

Westchester developed earlier and is more "old money"/"establishment"

Westchester and Bergen both have urbanized, more densely populated southern half and more exurban north half, while Nassau is both less urban and less "exurban"

Nassau is probably more old time "New Yawk"-ish in demographics while Westchester and Bergen likely attract more Manhattanites seeking a more suburban life and more transplants to the NYC area

 

[King of Kensington]

Both Nassau and Westchester have lost areas to NYC.

The Bronx was formed from the southern part of Westchester (that is why the former town of Westchester is in NYC). Queens shed its eastern part when it was incorporated into NYC.

Obviously state borders mattered.  Hudson County is often thought of as "the sixth borough."

[King of Kensington]

Demographically, Westchester is the least white, with its Hispanic and especially Black populations concentrated in the cities. 

Nassau has the most Blacks living in suburban settings I suspect though.

Bergen is the most Asian, due to the very large Korean population.  Nassau I believe has the most Indians and Chinese, and I suspect its proximity to Queens means it's likely to grow signficantly.  Few Asians in Westchester or northern NY suburbs.