Well, the Midwest is the geographical area around the intersection of the middle of the Northern Hemisphere and the middle of the Western Hemisphere. That's a mouthful though. Figuring most people would already know that they're about halfway between the equator and the North Pole, just by the weather, that part is implied and the tern focuses on referencing the midway point across the Western Hemisphere.
Most human beings aren't astute enough to make this association; so, you may not find any sources for this information other than me. I will endeavor to further everyone's understanding; however, by posting a link:
https://www.roadsideamerica.com/story/12005
No need to thank me. All in a day's work for
Bicycle Repairman (misconceptions repaired too).