When Jim Glaub first moved into his Manhattan apartment years ago, the previous tenants told him that the address had been receiving letters addressed to Santa for at least five years. 

"They never answered them because it was only three or four letters a year," Glaub told People. "And the first two years I lived there, it was that exact thing. I'd get three letters, and I didn't really think anything of it. I was like, 'Oh, sorry. Wrong number.'"

But by 2010, the number of letters had increased dramatically. That year, nearly 450 letters were addressed to Glaub's 22nd Street address in Manhattan.

"Kids think that Santa Claus lives in Chelsea," Glaub told the New York Times.

Glaub, 36, and his husband, Dylan Parker, 35, didn't know why the letters were addressed to their apartment, but they noticed a commonality: all the letters came from nearby neighborhoods and most of them came from families in need.

"These were our neighbors in the Bronx, Queens, Manhattan … These were our people," Glaub told People. "I just felt this need to help them."

That year, the couple enlisted the help of family, friends and social media users to answer 150 of the nearly 450 letters.

Since then, the number of letters addressed to Santa at the New York address has grown each year.

Glaub and Dylan, who moved out of the Manhattan apartment and out of the country, still answer the letters. They stay in touch with the current tenant of the apartment, who sends letters to them at their new home in London. They've committed to answering each letter received each holiday season and started a Facebook group to enlist the help of global volunteers. The volunteers are referred to as elves.

"It's gotten to the point where we can't not do it. We have to do it. It's just part of our lives," Glaub told People.

"It's all I can think about now during what is probably the busiest time in my life," he told the Times.

Glaub, Dylan and volunteers often send gifts to children who send letters.

See more at People and the New York Times.