The arctic blast gripping on much of the eastern US has begun to ease off, with winds calming and the weather warming slightly a day after temperature records - some more than a century old - shattered.
At least 21 people have been killed by the cold across the country since Sunday. Five died after collapsing while shovelling snow, while several victims were identified as homeless people who either refused shelter or did not make it to a warm haven soon enough.
All 50 states saw freezing temperatures at some point on Tuesday. That included Hawaii, where it was -8 C atop Mauna Kea, a dormant volcano.
In Atlanta, where a record low of -14 C hit, the forecast was sunny and a more normal 5 C.
The big chill started in the Midwest over the weekend, caused by a kink in the "polar vortex," the strong winds that circulate around the North Pole. The icy air covered about half the country by Tuesday.
With the bitter cold slowing baggage handling and aircraft refuelling, airlines cancelled more than 2,000 flights on Tuesday, bringing the four-day total to more than 11,000.
Natural gas demand set a record , eclipsing the mark set a day earlier.