At least 21 people have died in one of the worst cold snaps to hit the US Midwest in decades.
Ninety million people – a third of the US – have seen temperatures of -17C (0F) or below. Some 250 million Americans overall have experienced the “polar vortex” conditions.
Hospitals have been treating patients reporting frostbite as parts of the country ground to a halt.
Temperatures are expected to swing to above average over the weekend.
Homeless people have been particularly at risk, with warming shelters set up across cities.
But some still braved the freezing conditions and one woman, aged 60, was found dead in an abandoned house in Lorain, Ohio.
Some people were found dead a short walk away from their homes.
Officials said a Michigan man who froze to death in his neighbourhood was “inadequately dressed for the weather”.
In a wind chill of -46C (-51F) an 18-year-old student was found unresponsive a short walk from his dorm on Wednesday and later died in hospital.
On Tuesday, a man froze to death in a garage in Milwaukee, Wisconsin, having “apparently collapsed after shovelling snow”, according to a medical examiner.
Dangerous roads have also been a factor in the deaths. A man was fatally struck by a snow plough near Chicago on Monday and in northern Indiana a young couple died after a collision on icy roads.
The icy cold is expected to loosen its grip on Friday.
By the end of the weekend, Chicago could see temperatures as high as 10C (50F).
“It’s going to be at least a 60-degree swing for Chicago,” David Hamrick, a National Weather Service forecaster, told Reuters news agency.