The Maryland State Police (MSP) declares snow emergencies with input from MD State Highway Administration. Once a snow emergency is declared, the law requires certain precautions:
Prohibited parking on roads and streets designated as snow emergency routes; and The use of snow tires/chains (most cars now use all weather tires, so changing to "snow" tires is unnecessary)

Once an emergency is in effect, all requirements are in effect until lifted. A Snow Emergency Plan is put into effect by county. Certain exceptions can occur while a snow emergency plan is in effect. A specific route(s) can be lifted and the remainders of the roads in the county still remain under the Snow Emergency Plan. For the most up to date information, it is advised to call the local MSP barrack for the county.

Contact MSP