The feast day of Saint John the Baptist was a very popular event in the ancien régime of France, and it is still celebrated as a religious feast day in several countries, like Denmark, Norway, Sweden, Finland, Estonia, Latvia and Lithuania.
The tradition landed in Canada with the first French colonists. According to the Jesuit Relations, the first celebrations occurred on the banks of the Saint Lawrence River on the evening of June 23, 1636 with a bonfire and five cannon shots.
Historically, this date has been venerated in the practice of Voodoo. The famous Voodoo priestess Marie Laveau was said to have held ceremonies involving Voodoo ritual on the Bayou St John in New Orleans, commemorating St John's Eve. Modern day practitioners of Voodoo have kept the tradition alive.
Here is New Orleans VooDoo Priestess Sallie Ann Glassman's recounting of her first ceremony on Bayou St. John:
Bayou St. John ceremony
and more on herself:
Sallie Ann Glassman