The final breakup of the union of States in 1861 was preceded by over 80 years of conflict and compromise, and it was Southern statesmen who most often tried valiantly to save the confederation of the Founders. Just as colonial New England frequently antagonized England with its independently-minded maritime fleet, it often threatened secession and independence from the United States as it viewed its own interests as paramount to any other. The infamous Hartford Convention of New England Federalists seriously entertained secession in late 1814, and espoused States’ rights doctrines.
Bernhard Thuersam, www.Circa1865.com The Great American Political Divide
Southern Statesmen Save the Union
“The period from the ratification of the treaty of peace to the adoption of the Constitution has been called the critical period of American history; and the first year of that period was scarcely less critical than the last, the year in which, to use a familiar evangelistic expression, the Constitution was hair-hung and breeze-shaken over the bottomless pit.
It is scarcely to be doubted that at that time  the New Englanders in particular seriously contemplated the dissolution of Congress and the abandonment of the union of the thirteen States.
At such a time, when the bands of union were slipping, the centrifugal forces were everywhere running amuck, it was Thomas Jefferson who conceived the idea that the preservation of a “visible head” of the government was of supreme importance, lest, with the disappearance of even a symbol of the union, all faith and hope in a more perfect union should likewise perish; and it was the Southern members of Congress, nobly aided by Pennsylvania alone, who strove with might and main to combat the threatened peril.
Again, when men of the North would have hog-tied and bound the West and have delivered it into permanent subjection to the East, it was Southern statesmen, more than any others, who strove to establish the principle that the West should be carved into self-governing States, having equal rights in the union with the original thirteen.
Once more, in that long and hard-fought contest over the free navigation of the Mississippi River, when the North would have sold that American birthright for a mess of Spanish turnip greens and them frostbitten, it was Southern statesmen who saved the West to itself and to the nation.
During the contest over the navigation of the Mississippi . . . the forces of disunion again began slithering through the East. In the late summer of 1786 [James] Monroe was alarmed to discover that, in the very shadow of Congress, an intrigue was asquirm, the design of which appeared to be the disruption of the existing union and the creation of a Northern confederation that would extend, if possible, as far southward as the Potomac.
The scheme may have died a-borning . . . At all events there are grounds for suspicion that it was the same infant, waxed a bit stronger, that was exhibited at Hartford in 1814.”
(Southern Statesmen and the Confederation, Edmund Cody Burnett, North Carolina Historical Review, Volume XIV, Number 4, October 1937, NC Historical Commission, excerpts, pp. 357-359)