[WorldMaker]

The "flyover" areas have a lot more diversity than they are given credit for, including many of the cities smaller than Chicago. I don't think there is a US city of any size without pockets of interesting diversity. (Certainly none in my experience though I will admit to generally limited exposure to the Plains states and some "Midwest" bias.) Plus there are all sorts of large "contiguous statistical area" regions in "flyover" land that correspond to multiple "small" cities but overall have the same diversity/pockets/feel-ish of coastal CSAs. Chicago seems an interestingly over-large cut-off point to me for "diverse city" and may show some bias of inexperience in "flyover" areas.

There's definitely a startling lack of diversity in many of the US' truly rural areas, which is why the current US culture war seems dominantly city versus rural. But there are also fewer truly rural areas than people expect. (The US love of suburban and exurban expansion touched a lot of the country.)