I find it interesting, too, especially considering how the northeast is viewed by the rest of the country. That’s why I like to post that link whenever possible.
For both of you, with regard to Democrats and wealthy counties: I grew up in one of the wealthiest counties in PA - Montgomery County. But I grew up in a lower-income, working class town within that county. Our town was solidly Republican until, say, 20 years ago. Meanwhile, we worked and had relatives in the wealthier parts of the county, and they were mostly liberal Democrats. The Main Line was populated with Democrats at that time; at least, that was their reputation. I can’t find the numbers to back that up, though, and maybe their voting pattern has changed since then. Maybe napscoordinator is familiar with it.
1. The old line WASPs were replaced by nouveau riche Catholics, Jews, and even black folks who did not have the ancestral allegiance to the GOP.
2. As the GOP moved right on social issues, many "liberal Republicans" went independent or over to the Dems.
3. The more humble places like Norristown and (yeah, I know its in Delaware County) Darby became extensions of Philly's urban blight.
The same trends occurred on Long Island and in Bergen County.
Nevertheless, the pattern in NJ has remained. The wealthy, white collar (and heavily white and gentile) counties vote GOP, the cities vote overwhelmingly Dem, while the blue collar areas vote Dem, albeit not as heavily as the cities. The exceptions to the latter are places like Toms River, which have ALOT of police officers, who tend to lean right.
The "inner suburbs" (Tenafly, Fort Lee, Montclair, etc.) vote Dem largely due to their large Jewish, Asian, and ex-Manhattanite populations. Outside of this small strip, however, the GOP is strongest among the white, affluent, and gentile in this state.