>>> polar vortex , the fancy name on the cold, from the arctic well in the deep south in our country. a large and growing death toll is growing from this unusual and record-setting weather event, which thankfully is moderating some. we get our report from nbc's kevin tibbles in chicago.  >> reporter: a city tug chops its way along the chicago river keeping this water way open. while in new york's hudson river , a tug had to carve out a path to guide a stranded ferry through the ice. temperatures are dangerously cold throughout the midwest and northeast, 21 people have died as a result. but today, good news.  >> the polar air in place all week is finally starting to go back into canada. believe it or not by the weekend temperatures will be above freezing.  >> reporter: for thousands of chicago kids, the gradual warming meant an end to their unscheduled ice break .  >> not negative a thousand.  >> reporter: but many businesses froze in this big chill , too, and it is projected to cost the u.s. economy up to $5 billion, with 11,000 flights cancelled this week, the airline industry could take a $1.4 billion hit as travel plans were left in ruins and travel plans cancelled. as many snow bound in indiana, lost time is lost money , small businesses like this hot dog stand left out in the cold, as well.  >> we're only doing about 20% of what we normally do in sales.  >> reporter: the demand for heating fuel in the northeast hit a new high.  >> as you have to spend more to heat your home those are less dollars to take and spend on places like restaurants and movie theaters.  >> reporter: and taxis in some big cities are doing a booming business.  >> i did 40% better than normal.  >> reporter: when pipes froze in atlanta, this plumber's phone rang nonstop.  >> from 6:30 in the morning until 8:00 in the morning, we had 350 calls.  >> reporter: and calls increase, because when burst pipes break, basements flood. and brian, as this cold front finally appears to be snapping, amtrak says their trains should be running on time tomorrow. brian, does this really mean it might be over soon?  >> well, what a mess it has left behind . kevin tibbles
Video on msnbc.com: Temperatures remain dangerously cold across the Midwest and Northeast but the polar air is finally beginning to retreat.