Historians of the United States-indeed a lot of non historians even a lot of non Americans are used to thinking of the South as (at least historically) the truly unique area of the US. The area which (at least with it's white population) lost a war was poorer rather than richer than most of European history, that had a partly unique system of segregation through law ,that was monolithic Democratic for decades-and then swung hard and erratically to the Republicans-giving by far the best results to no Hooper Barry Goldwater. It should be noted there are powerful arguments that over the last few decades Southern exceptional ism has got a lot less salient for example in politics. The gap between the South and the rest of the United States has certainly shrank for example.
This is often extended to before the Civil War.And of course there was one enormous difference-slavery indeed with a few borderline exceptions that defined the South and it's history does today (some states like Delaware where slavery was very rare though legal and some states like Florida whose have had so much non southern migration) . In the rest of the nation's states chattel slavery of those of African descent had always been quite rare and was illegal by the 1830's-in most cases well before.
This was obviously hugely important-it was key in causing the Civil War after all! But it had loads of additional implications. Some were obvious a huge % (over a third) of the south's population was African American for example. Others followed the south was much less densely populated, much poorer per person (though not per white person-in capital terms South Carolina was the richest state in 1860) for example. It had huge impact on the South's nature-but at the same time virtual all the distinctions. There are arguable exceptions-the South had a strong "honour" culture That is the culture in which dueling or beating was the ultimate respectable resort to insult, the former in reaction to an equal the latter a subordinate. However this was arguably true of parts of the North too , and in any case that arguably owed something to the role physical violence played in slavery-and the perceived threat of slaves to a women's "honour".
However sans slavery on so many perceived differences the South actually fitted in much better. The South was not necessarily that anti tariff- Louisiana (whose products benefited from tariffs) was quite pro tariff for example and in the 1840's Southern Whigs voted similarly on Tariff bills to Northern Whigs. Southern "illiteracy" has been grossly exaggerated. It seems it was low density of population more than anything else that drove illiteracy-the sparsely populated states of Indiana looked very like the South in illiteracy. The worst illiteracy was in North Carolina- not the most "southern" southern state-but the least densely populated with the population spread among it's 100 counties. Politically it often voted like the nation- for example it was quite similar in the 1840 election and often though far from always swung on national ties- til the 1850's when slavery came to monomaniacally dominate political discourse.
On these issues there was another area that stood out more- New England. And it is to this I shall next turn.