I'd like to make a point about indentured servitude which they DID have in the north. The way it is taught in school it sounds like a sort of apprenticeship which could be hard at times.
The truth was it was a way around the anti-slavery laws and if you wound up in indentured servitude, you didn't get out, in fact you were lucky if your family got out. That's where that song "I sold my soul to the company store" comes from but the actual Northeastern IS was even worse.
Moreover, life was harsher for negroes in the North than in the south. The freaking damn yankee bastards still lie about the war, and everything else. They are the ones who are as bad as the french.
Along with that kind of suffering, the little-told tale of the Scots-Irish in the US at the time is also deafening.
What did someone do if they didn't want to risk a slave? (slaves were very costly and very valualbe, to both sides)
They sent in an immigrant (typically Scottish or Irish) and paid him nickles for a week's work (by today's standards)
They devalued other human lives, but noone talks about it.
And it was THE MO of the North from the 1830's to the early 1900's