Which of the following is not a national holiday?

Boxing day-this one can be confusing. the us used to celebrate both lincolns and washingtons birthdays separately, but the two holidays were combined into presidents day. since this day typically falls on or near washingtons birthday, ill call this a national holiday. martin luther king jr. birthday is a national holiday, but not all states celebrate it. labor day is a us national holiday. boxing day is a national holiday, but not in the us, so i marked that as the correct answer, since this is a us quiz.