The Washington Post did an article about how most mostly black neighborhoods voted more Republican in 2016 than they did in 2012. The white one is pretty interesting (it looks like a distorted X), but the black one is pretty bizarre too.
As you might expect, the higher the percentage of black people, the lower the percentage of Republican votes up to neighborhoods that are about 95% black. This trend flips, albeit slightly, at the very blackest neighborhoods, those which are 95% or more black. This is not a one time occurrence even though the sample size is small. This happened in both 2012 and 2016, as the top shows.