As an explanation as to how Canada rose to be a super-power, it could have been a massive enhancement in Canadian robotics with the result of having the majority of Canadian units being robots.
Or, as Canada currently has a small population but more land and resources than most countries on the earth, within the two-hundred years, massive flocks of people immigrated to Canada.
Or perhaps the Canadian and American factions could be merged, as it seems unlikely that those countries will become rivals at any point in time.