"The Revolution... was a needless and brutal bit of slaveholders’ panic mixed with Enlightenment argle-bargle, producing a country that was always marked for violence and disruption and demagogy."

"Look north to Canada, or south to Australia, and you will see different possibilities of peaceful evolution away from Britain, toward sane and whole, more equitable and less sanguinary countries. No revolution, and slavery might have ended, as it did elsewhere in the British Empire, more peacefully and sooner. No 'peculiar institution,' no hideous Civil War and appalling aftermath. Instead, an orderly development of the interior—less violent, and less inclined to celebrate the desperado over the peaceful peasant. We could have ended with a social-democratic commonwealth that stretched from north to south, a near-continent-wide Canada."

So the Civil War could have been avoided... if only the Revolution had been avoided.

That's the theory contemplated by Adam Gopnik in "WE COULD HAVE BEEN CANADA/Was the American Revolution such a good idea?" (in The New Yorker).