January 6 is the end of Christmas. That’s what I learned as a child. My family tradition was to keep the tree up until Epiphany. I thought it strange that so many others had bare trees on the devil strip on December 26 (having tired of the thing after putting it up the day after Thanksgiving?) or January 2 (start the new year “fresh,” according to an aunt). We had no other Epiphany tradition or observance - it just meant Christmas was over.
The other, and more personally important, related tradition was selecting the tree on December 14 (...