Not even middle America.
I grew up in Eastern Washington state, a place with a lot of farms and farmers. Due to that also a lot of immigrant labor.
I grew up in the “progressive” Pacific Northwest with lots of local businesses that had “English Only” signs, making clear to immigrants that they’re not really welcome in such establishments. It hasn’t really gotten better.
I’ve lived all over the country, and that distinction means nothing to anyone outside of the Northwest. Sure, it’s correct to call it that, if you’re being real pedantic, but if you go down South for instance, “Pacific Northwest” means Washington, Idaho, Oregon, and they still consider that region a whole lot more liberal than it actually is.
Secondly, having also lived on the west side of the Cascades… that’s less of a distinction than really matters. Like everywhere, it’s actually the cities that matter, and outside the cities its as racist and backward as anywhere else.
So I feel pretty confident in calling that the Pacific Northwest in what most average Americans would think of when they considered it. Not to say most Americans suck at geology and geography (that’s actually exactly what I’m saying) but I wouldn’t think most would be able to point to the Cascades on a map, let alone understand the distinction between the two.
So you’re correct in your quibbling, but also in the context of my response to OP, we’re talking about a reluctance to call middle America what it is: racist. I would think quibbling about saying “we already knew demographically that they’re not progressive” kind of misses that point.