The Klan started in Indiana. Also, Indianpolis/Marion county government was unified to keep the main urban area in the state competitive for Republicans; accordingly, a traditional Democratic machine never developed. Unions are significantly weaker in IN compared to other Midwestern states.
Thanks for the input! Those 4 states are the "oddest", just looking at the map of the US. At least in my head. Still looking for input on why Colorado&Nevada are blue, and why Idaho is red