Ohio

It makes more sense when you consider that for most of US history the country was significantly smaller than it is now. Originally the country pretty much just consisted of the East Coast - and France, England, and Spain still had large chunks of territory within the US's current borders.

Much of what's now considered the west wasn't captured from Spain/Mexico until much later. So basically just look at it from the perspective of the East Coast where the US originated. To them at that time what we consider the Midwest now would have just been the west. And the terms changed with the westward expansion.