While visiting Connecticut a strange old gravestone was pointed out to me.. indicating the date of this person’s death was “February 31, 1831”. This was very odd! Were leap years longer back in those days? Did February used to have 31 days back in 1831? After a bit of research, I discovered that February 31 was used when the actual date was unknown. Since February 31st is obviously not a real date….. it would be obvious to the viewer this was a placeholder date (sort of the “date” equivalent of “John Doe”). At any rate, the mystery is solved!