There Was a February 30 in 1712.
February 30 is the club’s name. It is open and if people have to wait to get in it is due to popularity, not because the date never comes.1
But February 30th was once a real date. It occurred in Sweden in 1712.
The date was added to correct an error in Sweden’s conversion from the Julian to the Gregorian calendar. Over the centuries the Julian calendar had fallen behind the seasons — to catch up you had to skip ten or eleven days.2 Most countries did it all at once, but Sweden wanted to adjust gradually by skipping ten leap years. The plan was adopted in 1700 and supposed to continue until 1740.
But almanac printers forgot to omit February 29 in 1704 and 1708. When the error was discovered, Sweden decided to go back to the Julian calendar. To do so it needed to add an extra day. February 30, 1712 was it.4 The image at the right shows February 30 as the entry at the bottom of the right page.