I might also add that the slide could have begun in the 1800's with Congress choosing to rely only upon tariff revenue to fund the US Treasury.
This, plus the formation of a free trade Confederacy, necessitated Lincoln forcing a war with the South.
Federal coercion over states' rights was founded in a financially strapped treasury, and began a tradition of statist expediency over Jeffersonian principles of individual rights.
So how do you think the confederate government would have been funded had there been no war? The new confederate government would have required some source of revenue, probably approaching the same levels as the old Federal government at first since they were creating an army and a navy and a postal system and all the rest from scratch. If they had been a free trade confederacy that would have removed tariffs as a source of revenue. I can't see them sitting still for an income tax - Davis had a hard enough time forced that through even with a war on. Sales taxes were unheard of. Excise taxes had caused rebellions in the U.S. before. How would they have survived?