The Nenana Ice Classic tripod tipped early Sunday morning, stopping the clock and making history as the earliest ending to the classic since it began in 1917.

Cherrie Forness, the classic's manager, said the tripod moved a short distance down the Tanana River late Saturday night, but not enough to stop the clock. It was hung up on a piece of ice, but began moving again at 12:20 a.m. Sunday morning. The ice broke up and stopped the clock just a minute later, at 12:21 a.m.

The classic is an Alaskan tradition, which started in 1917 when railroad engineers bet $800 to guess when the ice on the river would break up. From the start of February to early April each year, Alaskans buy tickets to guess the exact time they believe the tripod will move downstream, eventually tripping a clock that marks the end of the contest.

Officials with the International Arctic Research Center at the University of Alaska posted to Twitter that the clock stopped at record time this year — six days earlier than the prior record for earliest breakup. According to the official dates and times of the Nenana Ice Classic, the earliest breakup on record before this year was at 3:27 p.m. on April 20, 1940. The latest was at 2:41 p.m. on May 20, 2013. 

The IARC said this follows the warmest March on record in Alaska. On average, the Tanana River begins to freeze over during the months of October and November, when Alaska's full cold season begins. While prolonged cold and warmer months can have an affect on ice thickness, like we saw this year, on average the ice on the river is 42 feet by April 1.

A lot of factors are taken into account when it comes to just how the ice on the river freezes, but generally the ice melts on top due to the weather and on the bottom due to colder water rising from the depths of the river and freezing to the layers of the ice that are already there.

Forness said classic officials are going through sales now and will announce the jackpot winner, decided by the board of directors, on April 26. The prize money will go to whoever guesses the exact time the ice breaks, but Forness said there is usually more than one winner.

Aaron Morrison contributed to this report.

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