In this Times video, a couple that lives on West 22nd Street (the exact address was blocked) gets hundreds of letters addressed to Santa. The story does not really get into why they are getting the letters, abandoning that question to focus on the couple’s response.
But why would they receive all these letters? There has to be a reason. Theories? Is there something special about 22nd Street? Do we need to know the couple’s exact address?
http://video.nytimes.com/video/2010/12/24/nyregion/1248069482199/miracle-on-22nd-street.html
God works in mysterious ways. Santa Claus doubly so.
Besides, anyone who’s ever seen a holiday movie knows that Santa’s NYC address is 151 West 34th Street, where the eponymous miracle occurred. 
Someone gave out their address as being the mail-to address to Père Noël.
OMG! Santa Claus is gay, and he’s hanging around our children!
It gives the War on Christmas a whole new prospective.
The Children’s AID Society is located on EAST 22nd street, so maybe these letters should have been addressed to East 22nd and not West 22? Happens a lot in New York.
That would be reasonable except that they were addressed to a specific apartment within a building, not just a street address.
Gothamist has some other theories