"This guy is an elf in the sense that … elves are … people who were responsible for a lot of mischief," notes the New York Historical Society's Kathleen Hulser, who's traced Santa Claus' rise to fame in America.
She points out that. "Washington Irving wrote a book in 1809 in which he had a wonderful jolly character who smokes a long pipe, who comes from the Dutch tradition."
Mitchell says Irving's writings inspired the poem " 'Twas the Night Before Christmas." And a few years later, illustrator Thomas Nast, creator of the iconic "Uncle Sam" character, came up with the vision of Santa we know today.
As has happened to many of us, Santa's waistline has grown with each successive year.
Fortunately, observes Mitchell, so has his bag of toys.
And to Santa fanatics like Jeff Guinn, the-ever expanding story of Santa is itself a reason to celebrate.
"Christmas customs will always be evolving," Guinn says. "They're never going to be locked in one place. One hundred years from now, the way we celebrate Christmas … I'm sure there'll be some changes. That won't be a bad thing; that just means people are adding to the richness of the tradition."