If that's the margin in Detroit, is Sanders' improvement (or regional difference) among black voters getting overplayed? That result isn't much better than what we've seen in the south.
That is still about a 25% improvement for Sanders from the South.
Well, Detroit is 83% Black, which means that Detroit Democrats were probably at least 90% Black. Comparing that to the Black Belt counties with similar demographics (where Hillary got 85-90%), it does seem that Bernie has improved a bit (or does better outside the South).