I have borrowed the information and images below from Jeff Fecke at Alas A Blog. His discussion, if you’re interested, is more in depth.
There is a winding line of counties stretching from Louisiana to South Carolina, a set of states that largely voted for McCain in 2008, that went for Obama. The map below shows how counties voted in blue and red and you can clearly see this interesting pattern.
These counties went overwhelmingly for Obama in part because there is large black population. Often called the “Black Belt,” these counties more so than the surrounding ones were at one time home to cotton plantations and, after slavery was ended, many of the freed slaves stayed. This image nicely demonstrates the relationship between the blue counties and cotton production in 1860:
But why was there cotton production there and not elsewhere? The answer to this question is a geological one and it takes us all the way back to 65 million years ago when the seas were higher and much of the southern United States was under water. This image illustrates the shape of the land mass during that time:
I’ll let Jeff take it from here:
Along the ancient coastline, life thrived, as usually does. It especially thrived in the delta region, the Bay of Tennessee, if you will. Here life reproduced, ate, excreted, lived, and died. On the shallow ocean floor, organic debris settled, slowly building a rich layer of nutritious debris. Eventually, the debris would rise as the sea departed, becoming a thick, rich layer of soil that ran from Louisiana to South Carolina.
65 million years later, European settlers in America would discover this soil, which was perfect for growing cotton.
So there you have it: the relationship between today’s political map, the economy, and 65 million years ago.Lisa Wade is a professor of sociology at Occidental College and the co-author of Gender: Ideas, Interactions, Institutions. You can follow her on Twitter and Facebook.