document: The most extreme arctic blasts, blamed on a weather pattern known as the polar vortex, were said to have affected nearly 190 million people.
  In Kentucky, an escaped prisoner turned himself in to get out of the cold.
  Some parts of the Midwest hit -26C (-14F), as low as the Antarctic coast in winter, and much colder than the inside of a domestic freezer.
  Temperature records were shattered in states across the US, including Alabama, Georgia, Tennessee, Arkansas, Michigan, Maryland, Ohio, Pennsylvania and New York.
  It was -17C (1F) in the small town of Hell, Michigan, prompting online jokes that the weather was so bad even hell had frozen over.
  But it was Embarrass, Minnesota, that experienced the lowest temperature in the nation on Tuesday: -37C (-35F).
  That was colder than readings recently recorded on the Red Planet by the Mars Rover.
  A video of a meteorologist tossing a pot of boiling water into the air in Wisconsin, to demonstrate how it immediately turns to snow, quickly went viral on the internet and was widely imitated.
  A woman in Sioux Falls, South Dakota, was taken to hospital with severe burns after she slipped on ice while attempting the trick, spilling boiling water on herself, the Argus Leader newspaper reported.
  The extreme weather resulted in the usual travel chaos - nearly 2,700 US flights were cancelled on Tuesday.
  More than 500 rail passengers on their way to Chicago were marooned overnight into Tuesday morning in northern Illinois on three Amtrak passenger trains after drifting snow and ice covered the tracks.
  The big freeze was even testing the resolve of Canadians, no strangers to cold weather.
  Temperatures in parts of Ontario fell to -30C (-22F), causing flights in and out of Pearson International Airport to be halted for several hours on Tuesday morning.
  Roads in the cities of Toronto and Ottawa were coated in dangerous black ice.
  Freezing temperatures were recorded even in usually mild southern states.
  In northern Florida temperatures briefly dropped below freezing.
  Atlanta, Georgia, was 25 degrees below average for this time of year.
  "I didn't think the South got this cold," Marty Williams, a homeless man in the city, told the Associated Press news agency.
  "That was the main reason for me to come down from up North, from the cold, to get away from all that stuff."
  People in the Midwest are still digging out from two massive snow storms recently which dumped more than 2ft (61cm) of snow.
  A reprieve is expected soon, however, with forecasters predicting temperatures above freezing for much of the US in the coming days.
summary: Weather records have tumbled across North America, with freezing temperatures even in the southern US.