I have seen a number of elections, as I am sure many colleagues have. You're right that if it's the Thanksgiving Monday.... I think we voted on a Tuesday in an election when I was a candidate precisely because Thanksgiving Day was a holiday on a Monday. However, we didn't have the circumstances you described. Our legislation prescribes a three-day polling period finishing on a Monday, but I would think it would be far from ideal, as you say, to run over a statutory holiday in that three-day period. We don't have that many long weekends in a year.
However, I'd be happy to get a technical answer from Al Sutherland, if you want, who is listening now—