The US is bracing for another onslaught of bitter winter weather as a major storm gathers in the mid-west.
The storm is expected to affect a third of the country, stretching from Colorado in the country's centre to the north-eastern state of Maine.
Some 6,000 flights were cancelled on Tuesday, with more cancellations foreseen on Wednesday.
Nearly 27,000 homes in Texas and 14,000 in Ohio were without power, and storm alerts were issued in 19 states.
Officials in the city of Chicago, which is expecting 24in (60cm) of snow, said its public schools would close on Wednesday for their first "snow day" in 12 years.
In Missouri, more than a foot (30cm) of snow had fallen by midday, the Associated Press (AP) news agency reported, with more continuing to blanket the state.
Meteorologist Jeff Johnson of the National Weather Service in Iowa told AP the storm was sure to "cripple transportation for a couple of days".
The series of storms that has hit the US this winter is also wreaking havoc with government budgets. Clean-up costs are placing pressure on already tight public funds.
But other businesses are benefiting, with concerned residents stocking up on essentials.
"Milk, bread, toilet paper, beer," Todd Vasel, who works at the St Louis-based grocery chain Dierbergs, told AP. "It's been the equivalent of Christmas Eve, which is normally one of our biggest days of the year."
Hardware stores in affected regions have reported selling out of snow shovels, ice-melting salt and generators.
Oklahoma City and Tulsa, Oklahoma, were paralysed as the storm reduced visibility on the roads and snow drifts piled in drifts as high as 4ft.
More than 1,300 flights were cancelled in Chicago's O'Hare airport, among the busiest in the world. Another 350 were cancelled at the city's second airport, Midway.
Aviation officials warned that flights were likely to be badly affected on Wednesday too.
Some 900 flights were cancelled in Dallas, 650 in Newark, and nearly 1,100 at New York's LaGuardia and JFK airports.
"This storm is going to have a significant impact on airlines, particularly those with hubs in Chicago (United, American) and Newark (Continental)," the FlightAware website warned.