Compact Day celebrates the signing of the Mayflower Compact on November 11, 1620. However, because of the calendar shift from the Julian system to the Gregorian, during the 1600s ten days were "missing." That explains why the Society of Mayflower Descendants commemorates Compact Day on November 21 instead.

The Mayflower Society of Oregon's mid-November meeting focuses on the Mayflower Compact and the pilgrim Thanksgiving.