OOTL: The title is taken from Glen's excellent timeline.
Chapter One: The Sadness of Mother Liberty
Part I: The Loss of New England
When Washington lost the Second Battle of Boston he retreated to New York, and Burgoyne followed him with his army. At Albany, Washington's men lost a devastating loss to Burgoyne's soldiers. This marked the effective loss of New England*. There were a few more battles, most noticebly Yorktown, Saragota and Annapolis. The Peace of Madrid that ended the Anglo-Mysore War, it also established that New England stayed with Britain. Washington said later "The loss of New England is a loss to Liberty". Pan-Americanists often say that the New England region should be American, but by 1817, they had started to be closer to the Ontarians then the Pennsylvanians.
*New England in the TL includes New York.
OOC: The POD shall remain unknown OK?
I am flattered, of course, and the concept is an interesting one.
However, I am somewhat surprised that with so much of the 13 colonies (both states and population) under British control, that the USA came to exist at all. How did the US win this war with New York, Connecticut, Rhode Island, Massachussetts, and New Hampshire under British control? If they lost New York, how did they hold onto New Jersey, for example?
I think you can pull this off in some sense, but we either need a LOT more backstory, or perhaps a less expansive Dominion of North America (at least at first).
Okay, enough of my nitpicking. With so much of the US in British North America, you are looking at a USA that is dominated by the South, and especially Virginia. This is likely a USA that will hold onto slavery for a very long time. This is also a USA that is likely to be dominated by Baptists and Methodists over time. If you keep the butterflies to a minimum, you are likely to see a Louisiana Purchase of some sort (which reminds me, it will be interesting to see where the Western boundary of the US will be after the ARW), and a Texas takeover, as well as a likely war with Mexico (or whatever analogue of Mexico is there).
However, British North America so far is a powderkeg. There is nothing so far that makes me think that there's been a decrease of patriots in 'New England' for example. I could see a War of 1812 that in fact erupts into a New England Uprising - which quite frankly might be the only thing that will save the nascent USA from being completely beaten by the British. The aftermath of the uprising could be....unfortunate.
However, the winds of change can blow many a way, so I'll be interested to see where you take us.