Santa Claus has started his trek to deliver gifts to good children all across the globe. And for 70 years, a certain defense organization has helped share the status of his journey.

The North American Aerospace Defense Command, more commonly known as NORAD, has operated its Santa tracker since 1958. Today, the interactive tracker has its own website and mobile app, but in 1955, the defense organization received its very first phone call about Santa's whereabouts, all a part of a misunderstanding.

On Dec. 24, 1955, the then-Continental Air Defense Command Operations Center received a phone call from a child in Colorado Springs, Colorado, who wanted to know where Santa was. The child had seen a newspaper advertisement that provided a phone number for calling Santa, but the number was listed incorrectly. It instead sent eager children to the defense center responsible for tracking all North American air traffic. Despite the surprise the center may have encountered that year, the idea of a Santa tracker stuck, and it has for seven decades.

This Christmas Eve, President Donald Trump will assist about 1,250 U.S. and Canadian NORAD volunteers, fielding calls about Santa's travels at around 4:30 p.m. ET.