Around here, you can tell when there is the threat of winter precipitation. The salt trucks are out in force. They spread salt on overpasses and intersections before anything even starts falling from the skies. We take it for granted that the salt will magically prevent the roads and sidewalks from becoming too slick to drive or walk safely. Have you ever really thought of the science behind that magic?
Check out the salt and ice experiment from Only Passionate Curiosity.