The Thanksgiving holiday’s history in North America is rooted in English traditions
dating from the Protestant Reformation. It also has aspects of a harvest festival,
even though the harvest in New England occurs well before the late-November
date on which the modern Thanksgiving holiday is celebrated.

Thanksgiving, currently celebrated on the fourth Thursday in November by federal legislation in 1941, has been an annual tradition in the United States by presidential proclamation since 1863 and by state legislation since the Founding Fathers of the 
United States.

Norman Rockwell