Inside vs outside of the city and wealthy inner and middle suburbs is a far more massive cultural divide than red state vs blue state, nominal political party membership, rich vs poor or anything else.
From my own personal, subjective experiences, I've found this to be the big one. I've lived in 8 states now, in all regions except the Northeast, from big cities to smaller towns (SF to towns of ~30,000) and the rural vs. urban divide seems to be the most pronounced to me.
Yes, it's a pretty small town. My undergrad was approximately that size.
Of course, smaller exist! There are functioning towns in East Texas with less than 500 people in them! My favorite is Caledonia; cherished memories are that upon crossing the border my father would pull his best BB King impression and belt out the eponymous tune.
Hah, yeah I suppose it's relative. I guess a really small town I would think of having less than maybe 1,000 people, but 30,000 is about the smallest sized town I'd ever want to live in personally.
It's mostly urban vs rural, even on the coasts and in states like CA.
Visual: https://brilliantmaps.com/2016-county-election-map/