A winter storm is bearing down on the densely populated US north-east, after causing transport chaos in the South.
Across the typically mild South, more than 350,000 people lack power, and 3,800 US flights have been cancelled due to snow, ice and strong winds.
The storm has snarled traffic across the state of North Carolina and has already been blamed for 10 deaths.
The most crowded swath of the US - between Washington DC and Boston - is bracing for up to 1ft (30cm) of snow.
Even a snowplough found itself in tough driving conditions in North Carolina
The storm, described by the National Weather Service as an event of "historical proportions", leaves in its southern wake a wreckage of snapped tree limbs and power lines coated in as much as 1in (2.54cm) of ice, motorways turned to car parks, road accidents, and residents shivering in darkened homes.
Forecasters said it was one of the worst storms to strike Atlanta, the largest city in the South, since 1973.
President Barack Obama offered the might of the US federal government in aid, declaring a disaster in the state of South Carolina and all northern counties in Georgia.
On Wednesday evening, the Federal Emergency Management Agency (Fema) said it was moving supplies, including generators, meals, water, blankets and cots to an emergency centre in Atlanta.
Heavy ice brought down trees and power lines in Georgia
At least 10 deaths have already been blamed on the storm, including three people killed when an ambulance slid off an icy Texas road and caught fire.
Thousands of vehicles are backed up on snow-covered motorways around Raleigh, North Carolina, with some people abandoning their vehicles.
Soo Keith, of Raleigh, left her office shortly after mid-day, but after two hours had only driven a few miles.
Ms Keith, who is three months pregnant, told the Associated Press news agency she eventually abandoned her vehicle and continued on foot, arriving home four hours later.
"My face is all frozen, my glasses are all frozen, my hair is all frozen," she said.
"I know how to drive in the snow. But this storm came on suddenly and everyone was leaving work at the same time. I don't think anybody did anything wrong; the weather just hit quickly."
As much as one inch of ice was recorded in some parts of the South
Residents of Georgia appeared to have heeded official warnings, with motorways in the state clear but with many stuck at home without electric power.
"Thanks to the people of Georgia," Governor Nathan Deal said. "You have shown your character."
Mr Deal told those waiting for power to be restored to "be patient", saying he was hearing of "good response times" from the state's power companies.
The bad weather caused a run on grocery items, including milk, in Georgia
The vast storm is expected to bring snow as far north as Boston
Residents took to walking in Chattanooga, Tennessee
And schools were pre-emptively closed across much of the South