There also are a couple of things going on pre-rally. Camp Gears runs from Tuesday am to Wed pm for the official part, then the kids usually do things together the rest of the rally. Some were old enough to come by themselves, others were not. So families that came to bring the younger ones were on site early. I did volunteer shifts both before the official opening and during the rally.
This year seemed to be that there were a lot of other people on site mon-wed (fair people, grounds people, etc), and more non-two wheel vehicles all over the grounds. The Missouri State Fair is next month, and much preparation by fair people was going on, they backed off during our rally.
At this particular fair grounds, some of the roads withing the grounds were public roads, state maintained. I don't know the legalities of all of it, don't want to, but gate closings were during the time we 'rented' the grounds.