then the coast ran across the middle of the Carolinas, Georgia, and Mississippi.
This led to huge amounts of plankton and other tiny life being deposited there.
Which led to that area being the most fertile and heavily farmed as the US was colonized.
Which led to more slaves being brought to these areas.
Which led to these areas still being heavily represented by black populations, and since they were, over the years, the populations that couldn't afford to leave, as so many did, it also led to poverty. It is the blue line across these states in the map.
You can see the black belt in a TON of maps. It is really fascinating, especially as it is driven by geography at a time when the dinosaurs still had millions and millions of years left to live.
Article for those interested: