Signed on October 3, 1789, it calls on Americans to celebrate Thursday, November 26 as a day of thanks some years after winning independence from their former colonial masters, the British.
Thanksgiving, celebrated on the last Thursday of November, is perhaps the most iconic holiday in the United States that unites all Americans regardless of creed, color or income.
Auction house Christie's will auction off the manuscript, one of two known copies of the original document, in New York on November 14.
"His first proclamation calling for the day of Thanksgiving, an iconic American holiday and one that for Americans conjures image of our foundation... (is) going to resonate very powerfully with American collectors, and with collectors abroad we hope as well," he said.
Washington's annotated copy of the constitution fetched almost USD 10 million in 2012 and several of his letters relating to the constitution have sold for USD 1-USD 3 million.