Millions caught in icy grip as Arctic front pushes south

Besides snow and blowing snow, 80 million Americans will remain in the grip of icy cold temperatures for the next several days.  Dangerous wind chills are expected to linger through Wednesday.  On Monday, whiteout conditions forced schools in Sioux Falls, SD, to release students early.  

In Chicago, four inches of snow blanketed the city overnight Monday, and it was so cold that maintenance crews were forced to deice fire hydrants with blow torches.  There was also a concern about rail switches freezing on railway lines which can cause derailments.

Iowa received more snow which caused a crash involving at least 20 vehicles, which closed down Interstate 80.  In Wisconsin, wind chill values were near -35 degrees F.

CBS Story about cold