I agree. However, I will say that I always thought that Southern Indiana and Southern Ohio were more similar than Southern Indiana and Northern Indiana.

King George’s royal proclamation of 1763 established the “Indian Reserve” covering most of Ohio, Indiana, Illinois, Wisconsin, Michigan and Minnesota. European colonists were prohibited from trespassing - only a small number of British military outposts were allowed. Just a short time before the revolution, it got organized as part of Quebec.

Early in the revolution, it was taken by the colonists who declared it “Illinois County, Virginia” and allowed people to stream in and claim their homesteads (Note that the northern part was claimed by Connecticut as their own “Western Reserve”). Essentially all of southern Ohio, Indiana and Illinois was settled by people crossing the river from Kentucky, so it makes a lot of sense that you’d think that the southern parts of all these states seem more similar to each other than they are to their northern neighbors.

The next section north seems to have been mostly dominated by folks from the mid-Atlantic - Virginia, etc. And further north dominated by people that arrived on sailing ships, especially from New York. New Buffalo Michigan refers to Buffalo New York ;)

Anyway, it seems kind of weird that these states seem geographically oriented north-south but culturally oriented east-west. But the fact that they were depopulated (of Europeans) and then repopulated (by Europeans) gives an explanation of that, especially with the transportation available at the time of repopulation (of Europeans).

As someone who grew up in northern Indiana; 100%. Northern and middle-Indiana are pretty culturally identical, alongside southern Michigan, most of illinois, western Ohio, then extending further into e.g. southern Wisconsin and Iowa.

But southern Indiana is very different. Definitely more similar to Kentucky & Cincinatti-area southern Ohio. You start to get "twangs" of Southern Americana as you approach the Ohio River Valley, which are basically non-existent in northern Indiana. Something about the air is different.

The biggest cultural shock people not from the midwest, and even people from the midwest, often experience about the area is IME northern mainland/non-UP Michigan. Its a truly unique region that is dissimilar to almost anywhere else I've visited; like mixing the cultures of the New England coast with rural farms.