A massive winter storm stretching from New Mexico to Maine put 172 million people under winter-weather alerts for a weekend expected to paralyse parts of the southern US with ice and snow. More than 4,000 flights were cancelled on Saturday and in excess of 130,000 customers experienced power outages.

President Donald Trump approved federal emergency disaster declarations for 12 states: South Carolina, Virginia, Tennessee, Georgia, North Carolina, Maryland, Arkansas, Kentucky, Louisiana, Mississippi, Indiana and West Virginia.

The system delivered freezing rain and sleet into Texas, snow in Oklahoma, then moved northeast where forecasts called for up to a foot of snow from Washington through New York and Boston. State governors declared emergencies and urged residents to stay home as widespread travel and infrastructure disruption mounted.