This is not the first time such a merger, or union, has been proposed. A mordant-minded friend of mine has often suggested, with apparent sincerity, that the great tragedy of modernity is that Lincoln, stubborn to the point of paranoia, forced the South back into the Union, with all the death that caused, instead of letting it go, thus forcing American’s imperial affections northward. How that might have worked out for the remaining slaves is another, large, question.
via Canmerica the Beautiful: The Case for a U.S.-Canadian Union : The New Yorker.
Interesting that politics would continue to bring this idea into the temporal world. It's also interesting that many Americans have less of a penchant for Canadian culture and sensibilities than they might for British or Japanese artifacts. In this case it takes politics to move the thinking in the direction of cultural versus historical ties.
Not saying it's gonna happen by any measure, but it plays into this 'identity based on culture' path I've been thinking down.