EAGLE RIVER, WI (WXPR) -  It's the 50th anniversary year for what's considered the premier snowmobile racing event in the U.S. and the attractions are beginning in Eagle River.

The Amsoil World Championship Snowmobile Derby features an opening this weekend with the Vintage Snowmobile Weekend schedule.

Chuck Decker is the track owner.  He says practice begins Thursday for the vintage sleds with racing over the weekend and many great drivers returning.  "We're looking at probably record entries for both weekends, Vintage Weekend and Derby Weekend, and things are looking really nice.  There ought to be some really good racing.”  Decker says the melting conditions shouldn't be a problem.  "We make our own snow, so we have mountains of snow sitting on the infield for the snowcross course."  He says the ice oval is in good shape, too.

Eagle River Chamber of Commerce Executive Director Connie Heeg says the economic impact to the region from the weekends is large.  "We're expecting an extra large crowd for the derby, so we're really believing the economic impact for this whole two week period is going to be phenomenal.”

Chuck Decker says they usually get between three-thousand and five-thousand spectators during the opening vintage sled races. The derby on the following weekend will attract more than 20 thousand spectators.