This letter arrived at New York City's main post office in advance of Christmas on December 25. "Dear Santa Claus. Hi, how are you? Happy, Merry Christmas. I really need some pajamas for winter, and a big radio would be nice. You are the best man I have in my life, sincerely, Heidi." It is postal workers, and many other volunteers, who answer letters like Heidi's and help to make childhood wishes come true.

Each year, hundreds of thousands of New York-area children write letters to Mr. Claus, Santa, or St. Nick, the legendary, red-suited gentleman whose mythical home is the North Pole and who is said to drive a reindeer-drawn-sleigh delivering Christmas presents. But the grown-up reality is that most letters end up at the city's central postal facility.

For the past 15 years, Andy Sozzi, who works for the postal service in New York City, has donned a long white beard and played the role of St. Nicholas during Operation Santa, the postal service campaign to answer children's Christmas requests that come in at this time of year.

"It started with a bunch of clerks way back when in the 1920s that would see letters come by that were addressed to Santa Claus, and of course they were undeliverable," he explained. "And normal procedure was to throw those letters out because there was no place to deliver them and there was never any postage on them so they could not be returned. The clerks began feeling sorry for these kids, that they would have a bleak Christmas, so they would open them up themselves and act on Santa's behalf."

The children's letters are sorted by geographic location and language, and are then placed in boxes at the post office in midtown Manhattan. Volunteers are invited to come into the post office, and choose one or more letters to answer.

Vinnie Malloy, the postmaster for New York City, says the U.S. Post Office does not want to destroy the childhood belief in Santa Claus.

"The children believe in Santa Claus because they write the letters, they write letters to Santa Claus, so we just want to fulfill their wishes," she said. "They come in addressed to Santa Claus, and they say, North Pole. And they end up here at the James A. Fowler Building."

Sometimes, children ask for more than just a new toy, says Mr. Sozzi. "I remember one year, when a child wrote to Santa saying he was going blind and could not afford the operation, and a doctor from Columbia-Presbyterian heard about the letter, contacted the child and did the operation free of charge," he said.

For those children who write letters to Santa and expect a letter back postmarked from the North Pole? Well, the U.S. postal service can do that too.