The Pilgrim Proclamation:

Inasmuch as the great Father has given us this year an abundant harvest
of Indian corn, wheat, beans, squashes, and garden vegetables, and has
made the forests to abound with game and the sea with fish and clams, and
inasmuch as He has protected us from the ravages of the savages, has
spared us from pestilence and disease, has granted us freedom to worship
God according to the dictates of our own conscience; now, I, your
magistrate, do proclaim that all ye Pilgrims, with your wives and little
ones, do gather at ye meeting house, on ye hill, between the hours of 9
and 12 in the day time, on Thursday, November ye 29th of the year of our
Lord one thousand six hundred and twenty-three, and the third year since
ye Pilgrims landed on ye Pilgrim Rock, there to listen to ye pastor, and
render thanksgiving to ye Almighty God for all His blessings.  ~~
William Bradford, governor of the Plymouth Colony, 1623

It has seemed to me fit and proper that [the gifts of God] should be
solemnly, reverently, and gratefully acknowledged with one heart and one
voice by the whole American people. I do, therefore, invite my fellow
citizens . . . to set apart and observe the last Thursday of November
next as a day of thanksgiving and praise to our beneficent Father who
dwelleth in the heavens.
  -Thanksgiving proclamation, 1863  ~~   Abraham Lincoln

Thanksgiving was never meant to be shut up in a single day. ~~  Robert
Lintner