A 1/4 mile asphalt stockcar track was constructed in 1966 after the drag racing didn't take off nationally. A group of modified drivers came in from nearby dirt track Wilmot Speedway in Wilmot, Wisconsin after a dispute with insurance. In 1974, Larry Ninneman, who went on to win the track championship at the Slinger Super Speedway, was one of those drivers, and won 6 of 6 events entered. The corners had no banking, which permitted the drag strip to run through the center of the corner. The first modified race was won Pedro Roehl, and the first sportsman race was won by Dennis Burgan. The fast time in the modified cars was 17.58 seconds on the quarter mile. The track opened with a new grandstand for 10,000 fans and a new 300,000 watt lighting system. The modified cars later returned to Wilmot, and raced Saturday nights on the dirt at Wilmot and the asphalt at Lake Geneva on Sunday. Their ability to change setups gained widespread popularity that allowed the outlaw winged sprint cars to race in several states. Modified cars raced three nights per week, and late models were added to Saturday night programs.