Today in the United States is the Optional Memorial of Thanksgiving Day in the dioceses of the United States. In 1621 colonists in New England gave communal thanks and praise to God for his abundant mercies and blessings. This became a tradition and in 1863 Thanksgiving Day was proclaimed a legal holiday. It is celebrated liturgical with a Mass asking that each person's gratitude to God may bear fruit in loving service to neighbor. --Daily Roman Missal