(NewsNation) — As Christmas approaches, Santa trackers offer parents and kids a way to track the progress of St. Nick, but the first Santa tracker began after a typo in a newspaper ad.

NORAD’s Santa tracker began in 1955, but it wasn’t a planned affair. Col. Harry Shoup was on duty at the Continental Air Defense Command, now known as NORAD, when the phone rang.

But it wasn’t just any phone. At the height of the Cold War, the line that rang was a red phone with a number only known to high-ranking Pentagon officials. But when Shoup picked up, it wasn’t a general on the line.

Instead, it was a child calling to ask for Santa Claus.

According to his children, Shoup realized it wasn’t a joke when the child started to cry and began to play along. It turned out a Sears ad had printed a number where children could call to talk to Santa, but a typo meant the number listed was the top-secret line at the command center.

Shoup assigned some airmen to monitor the phone, acting as Santa Claus when people called in. On Christmas Eve, Shoup walked in to find a drawing of a sleigh and reindeer on a glass board the organization used to track planes.

Going with the joke, Shoup decided to call a local radio station and let them know the command had noticed a sleigh-shaped object pulled by eight reindeer on radar, providing updates through the night and promising the group would keep Santa safe on his journey around the globe.

Over the years, the tradition continued. Continental Air Defense Command became NORAD, a collaboration between the U.S. and Canada to monitor airspace over North America.

Now in its 68th year, the Santa tracker has evolved too, with a website and social media accounts to update families on Santa’s route.

People can still call in, and the hotline is run by more than a thousand military and Department of Defense employees and their families who volunteer to answer calls.

Shoup died in 2009, but his children said the man known as the Santa Colonel considered the tracker his biggest achievement, handing out business cards with the nickname and keeping a briefcase full of thank you letters from children in his later years.