which came to the U.S. through New Orleans, though the  gâteau des Rois (or the galette des Rois, depending on which part of France you're in) is not usually ring-shaped--more often log-shaped. I believe the Cajun tradition is for ring-shaped cakes, however.

In New Orleans, the custom is to have a king cake party on the Epiphany. Some families and organizations have a party every week from the Epiphany through Mardi Gras. In those instances, the one who finds the baby Jesus in his/her piece of the cake is not only the King or Queen of the party, s/he gives the next king cake party.