'Polar vortex' chills Chicago to the bone

Even the city's supply of its signature deep-dish pizza was affected: The Lou Malnati's chain announced it would stop taking delivery orders at 8 pm on Tuesday.

"I remember a cold winter like this in the mid-'80s," Jeff Kroin, 74, a researcher at the Rush University Medical Center who has been living in Chicago for more than 40 years, told China Daily.

"I remember I had my car parked on the street back then and had to run over every 15 minutes to start the engine so the battery wouldn't die," he added. "I'm so relieved that I have a heated garage now."

Kroin said that the medical center will require only essential staff, such as doctors in emergency rooms, to report to work.

The snow and winds also reduced visibility at O'Hare International and Midway airports, causing nearly 600 flights to be canceled.