Think it depends who owns and operates it. If the county runs it your GTG. If say the 4H owns and runs it it's essentially private property so they can say 'no guns.'
Here's a thread that you started last county fair season. Nothing has changed.So the Porter County Fair is coming up. What is the law on carrying there? Thanks ahead of time.
Most are county property, so you usually can't if your county has "County Property gun free zones" trust me I work at one and had a fight with one of your deputies when he told me at an event that a guy was carrying and shouldn't be and i told him to leave him alone.