
The Christmas movie tradition really took hold after World War II, when films like "It's a Wonderful Life" and "Miracle on 34th Street" gave families a shared story to return to every December.
Every generation since has added its own new classic to the rotation, until "watch a Christmas movie" became as much a household tradition as trimming the tree itself — something repeated on purpose, together, at the same time every year.
Old or new, the ones that stick are usually the ones watched with the same people, on the same night, more than once.