Just to expand on my questions a little, I'm curious how close the rebelling colonists came to uniting all of British North America. In retrospect, the invasion of Canada seems like a wasteful failure from the start, but that's based on 1) knowing the outcome and 2) viewing Canada and the USA as distinct nations. Was there a serious chance that the Americans could have taken control of Quebec? Had they done so, was there enough support for the revolution in Quebec that it would have joined?
I'm also curious how Quebec joining the revolution would have effected the course of later events -- would the war have ended sooner? would Quebec have joined in the Confederation and later Constitution, or would it have more likely pursued an independent course? -- but that might be too counterfactual for this reddit.
The support for the invasion was pretty low, for a simple reason; the British crown just gave almost everything the catholic clergy asked to back Britain. The British gave to the colony most of the important land to continue trading fur, the permission for the clergy to send people to Europe to ordain priests, archbishops, etc... and the right to keep french civil law. The act of Quebec (1774) was considered as a kind of last straw by the americans for war, but for the majority of the french canadian population, it was more than they could ask to be loyal to the British crown. The republican ideas, in this matter, were just not really interesting for the colony. Source: Le rouge et le bleu; Une anthologie de la pensée politique au Québec de la Conquête à la révolution tranquille, p32-43.
This sort of thing seems more appropriately asked in /r/HistoryWhatIf as this seems rather speculative, at least in part.
I think Nova Scotia was close but Halifax being magor British port for navy put a stop to it