Green- upper Midwest
Blue- Midwest
Red- border states that are not wholly in the Midwest, but have portions that are (for MO, the St Louis MSA, for KY, the Louisville MSA and Cincinnati MSA).
The Dakotas are not in the Midwest. They are Plains States.
Clearly you haven't been to the upper midwest much.
I strongly argue that the Upper Midwest is based around Minnesota and western Wisconsin, the northern half of Iowa, the eastern half of the Dakotas, the very far north of Illinois outside of Chicago, and the UP of Michigan.
Minneapolis/St. Paul is the capital.
There is no other interpretation.
It's probably because I'm from Southern Wisconsin, but I've always considered it to be exact same as you, but I would add eastern Wisconsin and the Chicagoland area.