I'd imagine New York, New Jersey, Connecticut, and parts of southern Hudson (depending on how far south the Hudson/LI border is; the
North America map has it in the Hudson Highlands, but the
world map has it up almost near Albany) being the third big regional group in the New England "mainland".
The scale on the world map may be a little off. Niagara state was formed with its border at the OTL counties of Cayuga, Onondaga, Cortland and western Broome (the Cortland-Chenango border extended due south), and with the capital at Geneva. Long Island state consists of Long Island, New York City, Staten Island, and the counties of Bronx, Westchester and Rockland.
More broadly, yes, it makes sense of New York, New Jersey, Connecticut (or most of it) and parts of southern Hudson to be drawn into a southern, mostly urbanised region.
Picturing the suburban infill between New York and Hartford, I can see Connecticut being far more densely populated, with suburban sprawl ballooning out from the nation's financial/trade capital (with the Erie Canal, New York's still likely to develop as such, even if it's not the Center of the Universe) and its political capital. TTL's New Jersey, basically, or New England's Essex. On a similar note, I can also see New York and Hartford being bitter rivals, especially in sports, much like New York and Boston in OTL. (A New York/Hartford rivalry doesn't preclude a New York/Boston rivalry from existing, mind. It could be three-way between them, even.) And given that Connecticut and western Massachusetts are pretty closely connected even in OTL, with Hartford and Springfield being seen almost as twin cities, western Massachusetts is likely to have even more affinity with Connecticut/Hartford ITTL, especially as Springfield grows, Hartford's sprawl starts to spill over the state line, and government workers start buying cottages in the Berkshires. It may be seen as "western New England" initially, but by the mid-20th century it's likely grown increasingly connected to the south. Either way, there's likely to be a pretty big western Massachusetts statehood movement, much like how OTL's New York has seen countless proposals to split it into two states.
That analysis makes sense. I'd add that while there is likely to be a big western Massachusetts statehood movement, I'm not sure whether it would get enough traction to be approved. The ATL split of New York state was a combination of the OTL statehood split sentiments, but with the disproportionate weight of New York state in ATL New England politics meaning that there was strong federal support for the split as well. (New York City more or less decided the presidency, due to the high population and the electoral college giving the overall state high weight, and New York City's higher population outvoting upstate New Yorkers.) The federal sentiment to split Massachusetts would be much weaker.
I'd imagine "southern New England" (New York/Hartford) being identified with the nation's elite, both political and economic, while "western New England" (Niagara, Hudson, and Vermont) is a stronghold of rural politics. Eastern New England would be the swing region; Boston and Providence would have a lot in common with New York and Hartford, but further north, you'd get a nation more resembling the rural west. Politically, this could go either way. On one hand, you could get a situation similar to OTL, where the rural areas are more conservative and the cities more liberal, with rural voters viewing the cities as decadent and city voters viewing the countryside as backwards. This happens a lot in OTL, throughout the world, so there is precedent. On the other hand, I remember Vermont and New Hampshire retaining socialist governments opposed to Hartford during the vitalist era, implying that there is a progressive streak in rural New England both economically and socially, while the cities could be identified with upper-class conservatism.
Rural areas in New England are in general more conservative, though it depends on the issue. The reason that Vermont and New Hampshire were socialist in the Vitalist era was that they were the strongholds of the old Federalists (conservatives), but that the Federalists were discredited due to supporting Mullins into the presidency, so they switched to the Socialists as the only viable alternative. Their Socialism had a rather values-driven streak, with a focus on philanthropy, helping out people in need, and so forth.
Again, not without precedent for New England; OTL's Vermont and western Massachusetts are probably more left-wing than the Boston suburbs nowadays, and New Hampshire has long been associated with libertarianism. It also wouldn't be the first flip from OTL's politics I've seen ITTL; I remember one update suggesting that the Catholics were identified with Prohibition, while the Protestants were against it. (Still trying to wrap my head around how
that one works, given how much of OTL's American temperance movement was intertwined with anti-Catholic nativist politics. That said, there were some
Prohibitionist sentiments in OTL among Catholics.) The different Prohibition movement could be a clue for political leanings; the cities and later suburbs where Catholics are presumably concentrated could have strong streaks of moralism and social reform, while the mostly Protestant countryside (especially farmers who grow the crops used to make alcohol) could lean towards "keeping big government out of your liquor cabinet" libertarianism. That said, a lot can change between 1933 and even, say, 1973, let alone 2013.
Political affiliations have certainly changed from their OTL equivalents in some respects. That said, TTL still has Catholic areas being more anti-Prohibition; that was touched on in chapter
#109 (footnote 4).
I don't know whether I ever mentioned this, but even from looking at a map, I'd guess that all the big cities in the NE (except Boston) will be smaller than IOTL. The border cuts through economic connections that exist IOTL, not to mention the danger of war.
This varies depending on what point in time they're being compared to. For the first few decades, New England had a higher population than in OTL, due to a higher proportion of European immigration to North America going there rather than the *USA, and because some New Englanders stayed home ITTL rather than migrating west as they did in OTL, since that would have been into parts of the *USA. Later on, lower birth rates (due to higher urbanisation) and greater willingness of some continental European migrants to go to the *USA means that they decline compared to OTL.
