The holiday stems from a feast held in 1621 by pilgrims from England who, with American Indians in what is now the state of Massachusetts, expressed gratitude for their well-being by commemorating a harvest after a harsh winter.
George Washington called for a day of giving thanks and prayers in 1789, though it was not annually celebrated until President Abraham Lincoln declared Thanksgiving a national holiday in 1863.
The holiday is ingrained in American life as a day for family gatherings with sumptuous turkey feasts. By one estimate, more than 43-million people are expected to travel 80 kilometers or more to attend holiday gatherings between now and Sunday.
Other Thanksgiving traditions are prominent in the U.S. as well, including religious services and key youth and professional football games.