"It is called the Midwest because of the location of those states in the 1800s before the U.S. expanded to the Pacific Coast. These states were part of the Northwest Ordinance. This term became obsolete once the U.S. expanded westward, resulting in these states becoming the Midwest."
Another site defines it as West of the Mississippi River, but between North and South. So I guess it qualifies.
I don't know if it's providence, algorithm, or confirmation bias, but I just ran into a four-day-old Namexplain video on this exact subject.
TLDR: it used to be the westernmost part of the country, called Northwest Territory, but then we got some more land farther west and changed the name, but then we got more land further further west and didn't.