I was looking into it and it says that the polls must close BY 9, but can close any time earlier if they want to.
All the rules sound like they were invented to encourage as much mayhem and chicanery as possible. Like Harry Reid wrote them or something.
I don’t know, our previous two caucuses were in the daytime with a stated period of time. With the amount of people voting tonight, I can’t see them closing before 9pm but maybe.