EDGERTON, Wis. --Road conditions have improved along a major interstate in southern Wisconsin after nearly 20 inches of snow fell on that area. On Wednesday, the winter storm snarled traffic for miles along Interstate 39 from Madison, Wisconsin, all the way down to near the Illinois state line. Dozens of cars and trucks couldn't get traction. They slid off the highway. They brought traffic to a standstill. At one point, nearly 2,000 motorists were stranded along that snow-covered interstate. Some of them were stranded for nine hours. Beginning around 4 p.m. Wednesday, a huge traffic jam had started, one that stranded nearly 900 people overnight. The sunshine revealed the cause of the problem. Semis were attempting to turn around on snow-covered highway shoulders, which is not recommended, according to one trucker from St. Louis. "That's a low percentage move. That would be your last resort," said truck driver Todd Smith. Smith got stuck at a truck stop in Edgerton, Wis., like so many others thwarted in their attempts to move and lock down when they found safety. "I tried to direct traffic and tried to get them rolling out of here, getting them out," said truck driver Tom Herrick, who helped out overnight. The National Guard and Red Cross assisted stranded motorists with food, fuel and blankets. There were no injuries. But Wisconsin State Police say they have lessons to learn from the jam. "Slippery conditions, snow that was in the area that you all know of, 17 to 21 inches plus drifts of two and three and four feet, we had challenges of getting those semi trucks up that grade," said Supt. David Collins, Wis. State Patrol. Through the morning commute, travelers inched along at no better than 10 mph as police tried to clear the interstate. It took until well into the afternoon before highway speeds were reached, which was a dream for someone barely able to escape the clutches of winter. Authorities are looking at how to handle situations like this better. They became aware of the traffic jam at 4 p.m., but there were those stuck as much as three hours before that.