In a game of Victoria 2, I added the Maritime provinces and New York State minus NYC, to a seceded New England. Now I am wondering about the actual plausibilityWhat would be the affects of Yankee Puritans expanding earlier into Canada, especially New Brunswick and Nova Scotia. With greater settlement, would those areas have seceded with the U.S.? Could an earlier spread of Yankee colonists into New England necessitated a split from New York. How else could there have been a larger New England. Could the entire world be Yankee? Or at least ruled by them?
From where I sit, in regards at least to the United States, who's to say it already hasn't been?
In any event, if you're looking at an independent New England (maybe a New England that encompasses the Eastern Seaboard after a much more different English Civil War/Interregnum, leading them to be the major power along the Atlantic coast, way before the US becomes a thing), I think you might have the capacity to build a large merchant empire IF they manage to get along with the UK at sea (nothing I see being a problem for them, and that's assuming there would be a UK to compete with after the butterflies take effect), which should help keep supply routes open. With that in mind, perhaps they can go a-filibustering in places like Africa, et. al. like the rest of Europe once that period of expansionism comes along, opening the way for more access to vital minerals and resources (even just getting in on OTL America's goods would be a decent boon).
As for being a part of the USA, and influencing the rest of America? I can see them being
relatively stronger compared to OTL (perhaps the Federalist Party can remain a more potent/longer-lasting influence on national politics past the 1810-20 timeframe); I repeat though, that the Northeast has long been the "metropole" of America in OTL, so I doubt you'd have THAT much more massive a jump in importance/influence without some rather early POD(s).