While this may be true for the old rite, the novus ordo Missal for the United States includes a proper Mass for Thanksgiving Day, with its own preface. The Gloria is not said.Yes, you can mark the day and even say a votive mass of thanksgiving, but it has no formal affect on the day’s mass.
To participate in the discussions on Catholic church music, sign in or register as a forum member, The forum is a project of the Church Music Association of America.