School Closed. Thanksgiving, or Thanksgiving Day, is a public holiday celebrated on the fourth Thursday of November in the United States. It originated as a harvest festival. Thanksgiving has been celebrated nationally on and off since 1789, after Congress requested a proclamation by George Washington. It has been celebrated as a federal holiday every year since 1863, when, during the American Civil War, President Abraham Lincoln proclaimed a national day of "Thanksgiving and Praise to our beneficent Father who dwelleth…