It is not the severity of the winter that affects roads and infrastructure, it is the type and that is true for Door County as well. Door County Highway Commissioner John Koldziej explains what will cause potholes come spring.
While salt may be bad for the undercarriage of your vehicle, it has a minimal effect on the roads you drive. Because of the hardness of pavement it can't adapt to moisture's expansion and contraction as the temperature wavers around the freezing point.