So, you guys have heard of the Great Migration, right? It's an important thing. Especially critical to keep in mind when thinking about Reconstruction. Also, slavery was banned from the Great Lakes states way back in the Articles of Confederation days. So, that's why outside of the big Industrial cities, there are still no black people in the farm country up that way.
It is hugely important and shaped the culture and politics of many of the northern cities. Chicago would be quite different without it.