Temperatures have plummeted as low as -40C in parts of America, making some states colder than Antarctica.
In Chicago, the average temperature is hovering around -17C, making it the second coldest day in 150 years. Locals have been warned "not to breathe deeply" outside amid the "deadly polar vortex".
The freezing temperatures have led to Lake Michigan freezing over to mesmerising effect.
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People have been sharing pictures on social media.
One traveller en route to Chicago O’Hare International Airport, which cancelled more than 1,500 flights over the past day due to extreme weather, took this photo while flying in.
One user likened the scene to the science-fiction disaster film The Day After Tomorrow.
In some footage, steam fog can be seen rising from the lake, which is created as the water temperature is higher than the air temperature, causing a "boiling cauldron" effect.
Meanwhile over the border into Ontario, Canada, Niagara Falls is also in the midst of a deep freeze, with parts of the iconic waterfall freezing over.
