would people of iowa have more in common culturally with people in those towns or more in common with people in Indianapolis?
You can swap out Indianapolis for many small towns in Indiana (or Ohio for that matter) then.
Cultural commonalities aren’t a good proxy for regional definitions, especially now as the lines between rural and urban are sharpening (more of a Cave topic). People in Boston, Atlanta, Chicago, and San Francisco live in very different regions but probably have more in common with each other than they do with people in rural New England, rural Georgia, rural Illinois, or rural California.