I've OC'd in Nebraska and nobody gave me a second glance. We've stayed overnight and done business around Hastings with no trouble at all.
Nebraska is fine, with the possible exception of Omaha. I've heard Omaha is their version of Denver.
Illinois.... you are wise to avoid altogether. Don't stray into the Land of Lincoln if you can work around it. Completely, totally, entirely antiConstitution.
They don't even uphold their own state Constitution, let alone the Constitution of the United States. The ISP (Illinois State Police) advocate using a rat-tail comb for self defense. A comb? Really????
We have kinfolk in Iowa but haven't been there since I started OC'ing. We likely will in September.
But I don't have experience with that state yet. However, I suspect OC would not be a problem.
So much of the state is rural to begin with, and cities few and far between, you'd be hard pressed to find anybody to get upset about it.
I know I haven't added much fodder for the neurons, but hope some of this helps.