The death toll rose after at least nine more people in Chicago were reported to have died from cold-related injuries, according to Dr Stathis Poulakidas, a doctor at the city's John H. Stroger Jr Hospital. Record-breaking cold hit northern IL early Thursday, when the temperature in Rockford dropped to negative 30 degrees (negative 34 Celsius).
The Postal Service took the rare step of suspending mail delivery for another day in many places.
Blame it on a polar vortex that's pushed temperatures to the lowest levels in decades, grinding major cities to a halt from Chicago to Park Rapids, Minnesota, where the wind chill hit 65 degrees below zero Wednesday.
"These [conditions] are actually a public health risk, and you need to treat it appropriately", Chicago Mayor Rahm Emanuel said Tuesday. "They are life-threatening temperatures, and they should be treated accordingly", he cautioned.
The most intense cold was expected overnight Wednesday into Thursday, said Ben Deubelbeiss, a meteorologist with the National Weather Service (NWS).
Sandwich shop manager Daniel Gonzalez, 37, also was required to report to work - at 5:00 a.m.
Mark Zandi, chief economist at Moody's Analytics, said one reason the severe cold weather will have less impact is that, unlike a hurricane, people did not lose electric power.
Chicago's regional electric train service was canceled due to wire problems caused by the freezing temperatures, as gas burners heated rail switches to keep trains moving on a reduced schedule.
More than 2,700 flights involving USA airports are canceled for Tuesday and Wednesday, including about 1,550 in and out of Chicago airports, according to FlightAware.com.
Even the U.S. Postal Service - despite its unofficial vow that couriers can not be stopped by "snow nor rain nor heat nor gloom of night" - was forced to suspend deliveries in some particularly frigid places.
The Polar Vortex can roughly be defined as a large area of low pressure and cold air surrounding both the North Pole and the South Pole.
Michigan Governor Gretchen Whitmer said government offices would remain closed through Thursday.
In Minneapolis, charitable groups that operate warming places and shelters were expanding hours and capacity 'as they do whenever unsafe extreme temperature events occur, ' said Hennepin County Emergency Management Director Eric Waage. The frigid air from the polar vortex in the US Midwest is forecast to expand to the city over the next few days.
The Arctic air will loosen its grip on the Midwest by Thursday afternoon; temperatures might even approach zero degrees in Chicago and Milwaukee.
"These are VERY DANGEROUS conditions and can lead to frostbite on exposed skin in as little as five minutes where wind chill values are below -50", the National Weather Service tweeted.
Warming centers were opened for vulnerable residents such as the elderly and shelter capacities increased for the homeless, including the approximately 16,000 people estimated to live on the streets of Chicago.
Burke Patten, spokesman for Chicago homeless shelter provider The Night Ministry, said some of the homeless were reluctant to go to shelters. "Here we are going right into spring-like temperatures".
More than 450 flights involving USA airports were canceled Friday - down from 2,300 the previous day.
"I'm here until they let me leave", Robinson told AFP.