In an article in Forbes, David Bressan writes that the giant rift in the USA’s political voting blocs is in part a consequence of collisions between continental plates, the literal giant rift that used to separate the two halves of North America, and recent glacial activity:
The same region that had once been covered in ocean water, leading to the fertile Black Belt, was almost an exact replica of the districts that had voted for Clinton.
The rich coal fields in Ohio, West Virginia, Pennsylvania and Maryland formed as a result of two continents colliding some 300 million years ago. The coal fueled the economic growth of cities like Pittsburg, Detroit, Chicago and Cleveland.
The Driftless Area is a region west to the Great Lakes that escaped glaciation during the last ice-age. Farming is more difficult here. The election map shows that most countries in the Driftless Area voted Democrats in 2012. It seems that more liberal politics, combined with financial hardship experienced by the local farmers and accentuated by the poor soils, convinced them to vote for Barack Obama.
Last year, astrobiologist Lewis Dartnell made a similar point in a Conversation at The Interval:
