The eastern half of the country has been hit by dense air known as a ‘polar vortex’ which has brought weather last seen two decades ago.
Parts of the north-east and Canada have seen up to 60cm (2ft) of fresh snow fall and 3,700 flights have been cancelled.
Schools in Chicago and other Midwest cities are closed and people have been warned to stay indoors. The city of Indianapolis has banned driving for anyone other than those seeking shelter.
Lake Michigan is frozen solid and ice breakers were deployed to clear the way for shipping.
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‘I have seen frostbite occur through clothing,’ warned Douglas Brunette, an A&E doctor in Minneapolis.
‘It’s not enough just to be covered. You need clothes made for the elements. You need to repel the wind.’
Indianapolis mayor Greg Ballard added: ‘The cold is the real killer here. In 10 minutes you could be dead without the proper clothes.’
Forecasters said some 187million people in all could feel the effects of the polar vortex by the time it spreads across the country.