No ordinance that I'm aware of, but we have always manned the door until 9 or until we run out of candy. Last year, we were in a new subdivision and had more kids than we'd had in 18 yrs combined at our previous house. Given that our mayor has waffled on a decsion (Sat vs Sun), saying that Sun is the day, but people are welcome to go out on Sat, we are prepared for guests both days (have a haunt that will be up and running both days). Once we shut down, we turn off all the outside lights (LR is in the back of the house, so you can't see anyone from the front), and quit answering the door.