In the Florida beach city of Pensacola, patches of ice sparkled in parking lots where puddles froze overnight. In Atlanta, which saw a record low of 6 degrees (-14 Celsius), fountains were frozen over, pipes burst and cars wouldn't start.
This is severely cold for these parts,'' said Brian Lynn, a National Weather Service meteorologist.
The cold broke records in Chicago, which set a local record Monday at minus 16 Fahrenheit (minus 27 Celsius), and elsewhere.
Forecasters said some 187 million people could feel the effects of the "polar vortex'' by the time it spreads across the US
In Toronto, a message on Pearson International Airport's official Twitter account Tuesday morning said "extreme cold (is) causing equipment freezing and safety issues for employees. Ground stop in effect until at least 9 a.m.''
PJM Interconnection, which operates the power grid supplying energy to more than 61 million people in parts of the Mid-Atlantic, Midwest and South, asked users to conserve electricity Tuesday because of the cold.
More than 15,000 customers in Indiana remained without power.
More than 500 Amtrak passengers spent the night on three stopped trains headed for Chicago because of blowing and drifting snow in Illinois, but rail officials said some began arriving in Chicago later Tuesday.
Bob Oravec, a meteorologist at the Weather Prediction Center in College Park, Maryland, said the blast of frigid air raised concerns that roads wet from melted snow from a weekend storm would freeze over.
But there are signs of things were returning to normal. Warmer temperatures, near or above freezing, were forecast for the Midwest.