Improbable.......................

    The United States in 1804 still felt improbable.  The states had been separate colonies for generations before they had bound themselves together in a federation a quarter of a century earlier.  The Constitution has been in force for fifteen years.  Travel between north and south was almost unheard of.  Thomas Jefferson never stirred more than a few miles north of Washington, nor did John Adams ever venture below it.  A citizen of Massachusetts might feel more at home in England than in Virginia or certainly than in Kentucky.  The forces that drove these men apart were strong, and the habit of accepting adverse political outcomes - even of believing in legitimate difference of opinion - was very new.  The power of Virginia would only grow over the ensuing years, and New England's leaders would seriously contemplate separation again in 1810, and yet again in 1814.  The doctrine of secession was born not in South Carolina, but in Massachusetts and Connecticut.  Adams would resist Northern threats to the union as fiercely as he later would the threat from the South.

-James Traub,  John Quincy Adams:  Militant Spirit