That wouldn't explain the pattern in the South, which is basically exactly the distribution of former slave areas https://en.wikipedia.org/wiki/Black_Belt_in_th

That wouldn't explain the pattern in the South, which is basically exactly the distribution of former slave areas https://en.wikipedia.org/wiki/Black_Belt_in_the_American_South https://en.wikipedia.org/wiki/Black_Belt_in_the_American_Sou... Socioeconomic status probably best explains that one, and is probably at least a component everywhere else. In any case, the geographic visualization on that page suffers from the same problem as electoral maps, where areas with very low populations (e.g the Texas border) occupy lots of visual space. The problem is really much worse in the South due to higher populations.