David Goldman, writing for CNN:

60 years ago, a local Sears (SHLD) store in Colorado Springs ran a dial Santa ad. Except the number was a misprint. Instead of listing the number for Sears’ Santa hotline, it posted the number for the Continental Air Defense Command center.

On Christmas Eve 1955, Colonel Harry Shoup began receiving calls from kids asking to speak with Santa Claus. Shoup worked at the operations department for the air defense center, now known as NORAD, so the call must have come as a bit of a surprise.

Instead of telling the kids that they dialed the wrong number, Shoup said that he wasn’t Santa Claus but he could track him on radar. All night, Shoup and his team fielded calls, giving kids details about Santa’s location as he and his reindeer flew through the sky to deliver gifts to children.

A tradition was born.

UPDATE: Or, if you prefer, you can go with this version [H/T Tuxbeej]