Shorter response:

Upper Midwest: Few, if any, slaves. Somalis who live in Minnesota immigrated from Africa, blacks in Chicago and Detroit immigrated there from the South during the Great Migration, etc. So almost all, if not all, blacks who live in this region VOLUNTARILY moved there.

Southern US: Lots of slaves. But, guess what, the Southern culture INCLUDES black culture. One reason there's been a re-migration of blacks moving back from places like Chicago to Atlanta.