Even the early, fully-racinated Congregationalist Yankees were like that.
The late historian Richard Hofstadter, while compiling his last, posthumously-published book (America to 1750, which he intended to be the first volume of a heavyweight, multivolume manual history), found the smoking gun of Yankee truculence against the South in the private journal of a Congregationalist minister who paid an extended visit to Charleston and surveyed its successful, bustling society in the mid-1600's, and found it utterly, utterly wanting. The frost on his comments adumbrate the Civil War. The Carolinians were, after all, Beyond the Pale. Which, to a Congregationalist back then, just about the whole world was, who were not among the Elect of the congregation.
Other Northerners reported similar experiences, including 22-year-old Abraham Lincoln in his 1831 trip down the Mississippi to New Orleans.
What they saw, in addition to slavery's cruelty, was that the more slavery dominated an area, the poorer it seemed -- to them.
In fact, most simply didn't understand the economics of what they were looking at.
Southern wealth was almost entirely tied up in its two biggest investments: land and slaves, and since land was quickly worn out growing intensive cash crops, there was a constant need to move on to newer frontiers, meaning the Southern landscape looked more "rough and ready" than more settled commercial ports of New England.
So the correct comparison should have been not frontier South vs settled Northeast, but rather Southern frontier vs Western frontier.
In that comparison, Southerners lived relatively more comfortably than their northern-western cousins.
But regardless of such early negative reports from Northerners, North and South got along well enough to defeat the British and write a new Constitution in 1787.
It's whole idea was to protect rights of individual states, while providing just enough Federal Government to insure a common defense and other minimum national necessities.
Point is: that North and South were different from the earliest days is not even debatable -- of course they were different.
But they were close enough to win the Revolution, establish a Constitution and survive as a nation for many decades.
What finally ended it in 1860 was fears by Deep South Fire Eaters, that Northern abolitionists would attack and destroy the "peculiar institution" on which their lives depended.
But abolitionism did not begin with Congregationalists ministers in the mid-1600s.
Abolitionism began centuries earlier, with the first English laws (i.e., 1102) and Papal Encyclicals (i.e., 1435) outlawing slavery in parts of Europe and the Americas.
So, abolitionism arrived in America before the first slaves did.