The state fair will NEVER allow firearms.
It's going to be an interesting legal question.
A conceal carry permit in Minnesota gives you the right to conceal carry throughout the state, unless otherwise restricted by law. So, the question is, where
can't you conceal carry?
You can't on federal property. You can't in schools, school buses, in school zones, or in day cares. You can't in courthouses, or in state buildings within the capitol area. You can't in state correctional facilities or in state hospitals.
You also can't, if it's a
private establishment (defined as a non-governmental property owned for non-governmental purposes) if that private establishment has complied with the posting requirements. You can't in churches, in peoples homes, or in colleges and universities, if they don't want you to.
It'll be interesting to see where, if at all, they can squeeze the state fairgrounds into those rules. The grounds are considered to be state property, iirc.