It is certainly true that the Large African/Black population of Mississippi is why it scores so poorly on so many comparative metrics. To think otherwise is simply PC based ignorance. Poor whites do better on aptitude tests than wealthy blacks, it is not simply an issue of "poverty".
Racial composition of a geographic area is highly predictive of all kinds of things. We can argue forever about "why" yet the underlying reality is what it is. Personally I don't give a damn as to "why" blacks do so poorly all over the world. I have an opinion based on what I think is the weight of evidence, but it does not really matter.
Either Blacks can elevate themselves or they can't, either way it will be by their own effort, it is proven that handouts from others have only made things worse with the culture of parasitism and dependency.
Toss the blacks out of Mississippi and give it to poor Chinese immigrants and it would not stay at the bottom for long. In fact it would become an economic and educational powerhouse, it is undeniable.