Around 10
10pm all the time unless you work there
9-9:30 but people stay until 1 is what a guy said. I just came back from there and it was still packed when we left at 4:30
I think most of the buildings close at 9:00, but I would bet that the midway is open later. I believe today is the last night of the fair so that might affect the hours.
Thanks! Your answer is awaiting moderation.