The very first Thanksgiving holiday was proclaimed by George Washington on Thursday the 26th day of November, 1789. So the history of the holiday as a Thursday in late November starts there - but it wasn't until 1863, in the troubled times of the Civil War, that President Lincoln made it an official annual holiday. And in 1939, FDR added one last calendrical tweak that establishes the observance of the holiday as we follow it today.
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