Video report by ITV News Washington Correspondent Robert Moore
The cold front is a result of a weather condition called a polar vortex.
The phenomenon is produced by a sudden blast of warm air in the Arctic, and North Americans need to get used to it as the polar vortex has been a frequent occurrence in recent years.
Last month, the normally super chilly air temperatures 20 miles above the North Pole rapidly rose by about 70C, due to air flowing in from the south.
This process is called “sudden stratospheric warming”.
That warmth split the polar vortex, leaving the pieces to wander, said Judah Cohen, a winter storm expert for Atmospheric Environmental Research, a commercial firm outside Boston.
“Where the polar vortex goes, so goes the cold air,” Mr Cohen said.
By Wednesday, one of those pieces will be over the lower 48 states of the US for the first time in years.
Officials throughout the Mid West are taking extraordinary measures to protect the homeless and other vulnerable people from the bitter cold, including turning some city buses into mobile warming shelters in Chicago.
Temperatures plunged as low as minus 32C in North Dakota with wind chills as low as minus 52C in Minnesota. It was nearly as cold in Wisconsin and Illinois.
"Avoid taking deep breaths and minimise talking" is the advice from officials in Iowa, a state that is experiencing -30C temperatures.
Governors in Wisconsin, Illinois and Michigan declared emergencies as the worst of the cold threatened.
The National Weather Service forecast temperatures in Chicago as low as minus 33C, with wind chills to minus 46C.
Authorities have now resorted to setting fire to train tracks to stop the metal from contracting.
“These are actually a public health risk and you need to treat it appropriately,” Chicago mayor Rahm Emanuel said. “They are life-threatening conditions and temperatures.”
Detroit’s outlook was for overnight lows around minus 26C, with wind chills dropping to minus 40C.
A wind chill of minus 32C can freeze skin within 15 minutes, according to the National Weather Service.
At least four deaths were linked to the weather system, including a man struck by a snow plough in the Chicago area, a young couple whose SUV struck another on a snowy road in northern Indiana, and a Milwaukee man found frozen to death in a garage.
The unusual cold could stick around for another eight weeks, Mr Cohen said.
“The impacts from this split, we have a way to go. It’s not the end of the movie yet,” Mr Cohen said. “I think at a minimum, we’re looking at mid-February, possibly through mid-March.”
Americans were introduced to the polar vortex five years ago. It was in early January 2014 when temperatures dropped to minus 27C in Chicago, and meteorologists, who used the term for decades, started talking about it on social media.
This outbreak may break some daily records for cold and is likely to be even more brutal than five years ago, especially with added wind chill.
And while the US Midwest chills, Australia has been boiling to record-breaking heat. The world as a whole on Monday was 0.4C warmer than the 1979-2000 average, according to the University of Maine’s Climate Reanalyser.