As a person who was born and raised in the Midwest[1], just where are these mountainous regions they speak of in the Midwest? There's the black hills[2] and that's pretty much it. I wonder what definition of the Midwest the University of Cambridge is using, cause it sounds like they are talking about the intermountain west[3], not the midwest.
[1]: https://en.wikipedia.org/wiki/Midwestern_United_States