FAIRBANKS, Alaska -

Alaska's biggest guessing game has begun.
    
Workers set up a tripod Sunday on the Tanana River in the tiny community of Nenana, about 55 miles south of Fairbanks.
    
As soon as the ice begins to move, the tripod tips on the shifting ice and stops a clock.
    
The 98-year-old game is a popular form of wagering in Alaska, drawing entries from across the state and elsewhere.
    
The Fairbanks Daily News-Miner reports several dozen spectators watched Sunday as crews raised the tripod on the ice, which usually moves between late April and the first two weeks of May.
    
People pay $2.50 a guess to predict when the ice goes out in the river.
    
Last year's classic produced a jackpot of $318,500.

The tripod can be monitored online on the Ice Classic webcam.