The Midwest is better these days regarding seafood, but back when I was growing up, you'd be lucky to find even frozen fish, except for Gorton's fish sticks. Canned tuna was also available and that was about it. If you wanted to eat seafood, you had to go to a restaurant.
I sometimes think your experience of the Midwest was somewhat different from mine. But I bet fish sticks were the main form of seafood in them days anywhere in the country that wasn't near an ocean. Quick shipping might not have been available, and I don't think Americans in general were very sophisticated eaters in general. Thank goodness for Julia Child and Alice Waters!
Every spring my parents would get a big bag of smelt -- little fish that rushed through northern rivers in the spring, cooked breaded and fried. I never hear of them now, so maybe they were overfished. We ate fish, like walleye, caught by people who fished, like my aunt and her partner. My mom sometimes made scallops but I didn't like them (not until recently, in fact). When I was about 18, my friends and I started going to what I then regarded as fancy (chain) seafood restaurants, and those all-you-can-eat crab leg places became a trend.
But food everywhere is more sophisticated these days. The only place I've been that stands out as being much more sophisticated than other cities is New Orleans. In regard to food, that is, not necessarily anything else.
I also think Catholics may have a different experience of fish. My friend who spit out the smoked fish spread grew up Catholic and I think hated fish for that reason. My folks was atheists (or agnostics, or Unitarians or whatever), so we didn't even do Lent, let alone fish on Fridays.
Oh, I just remembered one thing, though. When I lived in Duluth, MN, in the '80s, an upscale Italian restaurant opened with interesting food like carpaccio. But they had a billboard that -- I can't remember the exact wording but it was meant to reassure potential customers that not all their food was weird and foreign. So they had a picture of a steak. But the weird and foreign Italian food was ... spaghetti and meatballs.

Sorry, Chuck. I think even Duluth residents of the '80s were pretty familiar with spaghetti, if only thanks to Chef Boyardee!