Black voters typically support the Democratic party, which is popular in Alabama’s middle districts. That vote shows up in electoral maps as a stripe running straight through the GOP stronghold: The black belt.
Contrary to myth, the “black belt” does not refer to the large African American population living in the area—or at least it didn’t originally.
“Black belt” refers instead to the quality of the soil of the area. Tanks to ancient marine deposits, the soil of that area is rich in nutrients, extremely fertile and, indeed, black. And there is a direct link between the color of the soil and the political leaning, too: Cotton.
As biology professor Allen Gathman shows by overlapping Alabama’s cotton production by county in 1860 (when the production was heaviest in Alabama, Mississippi, and Louisiana) with the 2016 presidential election results, the areas with historically strong cotton cultivation, and therefore a historically large population of black laborers in the second half of 1800s correspond to Democratic votes today.
So, you can explain where Democrat support in Alabama is located in the present by looking at the race of voters. In turn, you can explain the racial makeup of the state by looking at the economy (and specifically where cotton production was located) more than a century ago. And that in turn is explained by the nutrient content of the soil.
These kind of geographic/geological factors tend to wind up underlying everything else. Indeed, the very first lecture of my history degree began with this map and the rather startling conjecture that it explains most of global inequality.
The lecturer used it to illustrate Jared Diamond’s argument that:
Continents that are spread out in an east-west direction, such as Eurasia, had a developmental advantage because of the ease with which crops, animals, ideas and technologies could spread between areas of similar latitude.
Continents that spread out in a north-south direction, such as the Americas, had an inherent climatic disadvantage. Any crops, animals, ideas and technologies had to travel through dramatically changing climatic conditions to spread from one extreme to the other.
Technologies such as gunpowder were able to migrate 6,500 thousand miles from China, where they originated, to Western Europe, where they reached their apogee, in a matter of centuries. The wheel, on the other hand, developed in southern Mexico, never even managed the 500-mile journey south to the Andes.
This generally isn’t what we like to focus on when we contemplate history. Individuals and movements are more relatable. However, it pays to be aware of the context in which individuals and movements operate and how powerfully that is shaped by geography.