Well John, I think it's Russian Orthodox Christmas that is about two weeks into January...........that might be your answer.
I had a friend when I lived in Jersey who's family was Russian, and they used to leave their tree up until about the third week in January. I know Xmas tree dealers in areas where there a lot of Russian families don't discount their trees well after Christams because they get snatched up by those who celebrate the Russian Christmas.
As far as Kwanza, I only know cause it happens to be on a calender I have at home.
It's also Boxing Day today....anybody know what that's about.....here's a hint.....albeit a vague one...year's ago, on "Punch the Clock", Elvis Costello sang:
"And from this day, every day will be Boxing Day........."