At which point were the Northern and Southern US states first considered as the different cultures we know today? Did this happen during the Civil War or was there a distinction earlier? When did the Mason-Dixon Line become the "border" between the two? I have never lived in the US so please forgive my ignorance if this is considered common knowledge.
When Edmund Burke spoke about the taxation in the American colonies (so shortly before the Revolution), he already mentioned a cultural difference:
" It is, that in Virginia and the Carolinas they have a vast multitude of slaves. Where this is the case in any part of the world, those who are free, are by far the most proud and jealous of their freedom. Freedom is to them not only an enjoyment, but a kind of rank and privilege. Not seeing there, that freedom, as in countries where it is a common blessing, and as broad and general[182] as the air, may be united with much abject toil, with great misery, with all the exterior of servitude, liberty looks, amongst them, like something that is more noble and liberal. I do not mean, Sir, to commend the superior morality of this sentiment, which has at least as much pride as virtue in it; but I cannot alter the nature of man. The fact is so; and these people of the Southern Colonies are much more strongly, [[241]] and with an higher and more stubborn spirit, attached to liberty, than those to the North-ward. "
"Speech of Edmund Burke, Esq., on Moving His Resolutions for Conciliation with the Colonies, March 22, 1775"
http://oll.libertyfund.org/titles/796/20354
I am not American either, but to me this passage in 1775, basically the idea that slave-owners are more likely to be rebels, looked strangely prescient. Almost like the prediction of the Civil War.