A Pennsylvania snow emergency is when the governor, or other authority figure, declares that it is unsafe to be on the roads when a substantial amount of snow falls. Some roads and highways are closed to non-emergency traffic, unless the vehicle has tires that are rated for snow or mud.
A snow emergency route will be posted as such. Any vehicle driven on a snow emergency route must exhibit at least two tires with the rating of mud and snow visible on the sidewalls or tire chains on the drive axles.
Townships and cities in Pennsylvania have additional ordinances for snow emergencies. For instance, in the Township of Upper Gwyneed, public streets are to be free of parked vehicles to allow for snow plows and emergency crews.