Suppose that the USA broke apart sometime in the 10 or 20 years after winning independence, and one of the independent nations that emerged was an independent New England. I mean only the territory that was or later became the 6 New England states of Massachusetts, Connecticut, Rhode Island, New Hampshire, Maine, and Vermont. (I loved Decades of Darkness, but I have a different, smaller nation in mind compared to the New England of that timeline. 
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This is a series of questions rather than a specific timeline. The questions fall into several categories.
Economics - Would being a separate nation be likely to help or impede economic development compared to the New England states of OTL, or would it likely have little effect one way or another? Would an independent New England still be the first place in North America to start building true industrial factories for the textile industry? Would being in a separate country from the states supplying cotton for textiles be a severe handicap, or would trade with cotton-growing states likely thrive just as much as if they were part of the same nation? Would the course of industrial development of an independent New England be similar to OTL, in which an early leading role was gradually lost to other parts of the USA, and the New England states came to focus on "light" industries or more specialized industries, due to a lack of local raw materials for heavy industry and a relatively high cost of labor? If an independent New England followed a different course, what would be some of the likely alternatives?
Politics - What type of government would an independent New England likely have? Since in OTL New England was the greatest stronghold of Federalists who wanted a relatively strong central government, would an independent New England likely have a stronger federal government than OTL USA or the other nations that formed from the former USA? Would the advocates of strongly centralized government have to compromise and establish a weaker central government in order to bring in Rhode Island, which was often at odds with the other New England states, and possibly also Vermont, which was independent minded enough to almost declare itself a separate country after the American Revolution? Would Maine likely become a separate state as in OTL, or would it be more likely to remain a part of Massachusetts?
International relations - Would an independent New England be likely to have very close relations with the other nations that made up the former USA, or would it be likely to draw closer to Britain over time, possibly becoming almost a satellite state? Would New Englanders still become a major trading presence in much of the world for most of the 19th century?
Culture - Would cultural developments be similar to OTL, or would being a separate nation cause major changes in culture? Would Boston still become a significant intellectual center? Would New England writers and intellectuals have a significant influence on other nations in North America and even beyond, or would they be little known outside their own country in comparison to OTL? Would New England still be known as a center of new religious and social movements in North America, or would its culture be more conservative?
Demographics - Would an independent New England attract as many immigrants as the New England states did in OTL? Would Irish Catholic immigrants still become a major fraction of the population in the mid-19th century? Would large numbers of "old Yankee" English Puritan-descended New Englanders still move to upstate New York, northern Ohio, Michigan, or even the Pacific Northwest if those areas were parts of separate countries, or would more of them stay in New England proper or move in different directions?
Any thoughts and/or speculations are welcome.
)This is a series of questions rather than a specific timeline. The questions fall into several categories.
Economics - Would being a separate nation be likely to help or impede economic development compared to the New England states of OTL, or would it likely have little effect one way or another? Would an independent New England still be the first place in North America to start building true industrial factories for the textile industry? Would being in a separate country from the states supplying cotton for textiles be a severe handicap, or would trade with cotton-growing states likely thrive just as much as if they were part of the same nation? Would the course of industrial development of an independent New England be similar to OTL, in which an early leading role was gradually lost to other parts of the USA, and the New England states came to focus on "light" industries or more specialized industries, due to a lack of local raw materials for heavy industry and a relatively high cost of labor? If an independent New England followed a different course, what would be some of the likely alternatives?
Politics - What type of government would an independent New England likely have? Since in OTL New England was the greatest stronghold of Federalists who wanted a relatively strong central government, would an independent New England likely have a stronger federal government than OTL USA or the other nations that formed from the former USA? Would the advocates of strongly centralized government have to compromise and establish a weaker central government in order to bring in Rhode Island, which was often at odds with the other New England states, and possibly also Vermont, which was independent minded enough to almost declare itself a separate country after the American Revolution? Would Maine likely become a separate state as in OTL, or would it be more likely to remain a part of Massachusetts?
International relations - Would an independent New England be likely to have very close relations with the other nations that made up the former USA, or would it be likely to draw closer to Britain over time, possibly becoming almost a satellite state? Would New Englanders still become a major trading presence in much of the world for most of the 19th century?
Culture - Would cultural developments be similar to OTL, or would being a separate nation cause major changes in culture? Would Boston still become a significant intellectual center? Would New England writers and intellectuals have a significant influence on other nations in North America and even beyond, or would they be little known outside their own country in comparison to OTL? Would New England still be known as a center of new religious and social movements in North America, or would its culture be more conservative?
Demographics - Would an independent New England attract as many immigrants as the New England states did in OTL? Would Irish Catholic immigrants still become a major fraction of the population in the mid-19th century? Would large numbers of "old Yankee" English Puritan-descended New Englanders still move to upstate New York, northern Ohio, Michigan, or even the Pacific Northwest if those areas were parts of separate countries, or would more of them stay in New England proper or move in different directions?
Any thoughts and/or speculations are welcome.