GALLERY: 'Polar vortex' hits US

The Chicago skyline is framed by icicles in Chicago, Illinois, January 8, 2014. Photo: REUTERS/Jim Young.
The Chicago skyline is framed by icicles in Chicago, Illinois, January 8, 2014. Photo: REUTERS/Jim Young.
Jennifer Berry watches the sunset from a lifeguard chair at a beach on Lake Calhoun in Minneapolis, January 7, 2014. Photo: REUTERS/Eric Miller.

Jennifer Berry watches the sunset from a lifeguard chair at a beach on Lake Calhoun in Minneapolis, January 7, 2014. Photo: REUTERS/Eric Miller.

Cyril River races his dog, Aldo, as he skates around Lake of the Isles in Minneapolis, January 8, 2014. Photo: REUTERS/Eric Miller.

Cyril River races his dog, Aldo, as he skates around Lake of the Isles in Minneapolis, January 8, 2014. Photo: REUTERS/Eric Miller.

Barry Tilton cleans the snow off of his pick-up truck in the midtown neighborhood of Detroit, Michigan January 6, 2014. Photo: REUTERS/Rebecca Cook.

Barry Tilton cleans the snow off of his pick-up truck in the midtown neighborhood of Detroit, Michigan January 6, 2014. Photo: REUTERS/Rebecca Cook.

Ice forms on the shore of the East River due to unusually low temperatures caused by a polar vortex in New York January 7, 2014. Photo: REUTERS/Lucas Jackson.

Ice forms on the shore of the East River due to unusually low temperatures caused by a polar vortex in New York January 7, 2014. Photo: REUTERS/Lucas Jackson.

Women bundle up against the cold one block from the White House as temperatures plunged along the East coast due to the "polar vortex" of dense, frigid air in Washington January 7, 2014. Photo: REUTERS/Larry Downing.

Women bundle up against the cold one block from the White House as temperatures plunged along the East coast due to the "polar vortex" of dense, frigid air in Washington January 7, 2014. Photo: REUTERS/Larry Downing.

A worker spreads sand near an exterior waterfall that froze overnight at the National Museum of the American Indian in Washington January 7, 2014. Photo: REUTERS/Gary Cameron.

A worker spreads sand near an exterior waterfall that froze overnight at the National Museum of the American Indian in Washington January 7, 2014. Photo: REUTERS/Gary Cameron.

A woman walks through a gust of blowing snow in frigid cold temperatures though downtown Chicago, Illinois, January 6, 2014. Photo: REUTERS/Jim Young.

A woman walks through a gust of blowing snow in frigid cold temperatures though downtown Chicago, Illinois, January 6, 2014. Photo: REUTERS/Jim Young.

A woman walks through a gust of blowing snow in frigid cold temperatures though downtown Chicago, Illinois, January 6, 2014. Photo: REUTERS/Jim Young.

A woman walks through a gust of blowing snow in frigid cold temperatures though downtown Chicago, Illinois, January 6, 2014. Photo: REUTERS/Jim Young.

A man clears snow from his car in Indianapolis, Indiana January 6, 2014. Photo: REUTERS/Nate Chute.

A man clears snow from his car in Indianapolis, Indiana January 6, 2014. Photo: REUTERS/Nate Chute.

A snow plow clears the road on Interstate 65 north of Indianapolis, Indiana January 6, 2014. Photo: REUTERS/Nate Chute.

A snow plow clears the road on Interstate 65 north of Indianapolis, Indiana January 6, 2014. Photo: REUTERS/Nate Chute.

Ice from the breath of Gail Davis forms around her face as she exercises by walking outside in Minneapolis, January 8, 2014. Photo: REUTERS/Eric Miller.

Ice from the breath of Gail Davis forms around her face as she exercises by walking outside in Minneapolis, January 8, 2014. Photo: REUTERS/Eric Miller.

A snow covered scooter is seen in Chicago, Illinois, January 8, 2014. Photo: REUTERS/Jim Young.

A snow covered scooter is seen in Chicago, Illinois, January 8, 2014. Photo: REUTERS/Jim Young.

A man walks along a snow covered beach in Chicago, Illinois, January 8, 2014. Photo: REUTERS/Jim Young.

A man walks along a snow covered beach in Chicago, Illinois, January 8, 2014. Photo: REUTERS/Jim Young.

A man is framed by icicles as he walks along a beach in Chicago, Illinois, January 7, 2014. Photo: REUTERS/Jim Young.

A man is framed by icicles as he walks along a beach in Chicago, Illinois, January 7, 2014. Photo: REUTERS/Jim Young.

A man walks beside a frozen wall on a beach in Chicago, Illinois, January 7, 2014. Photo: REUTERS/Jim Young.

A man walks beside a frozen wall on a beach in Chicago, Illinois, January 7, 2014. Photo: REUTERS/Jim Young.

A man is framed by icicles as he walks along a beach in Chicago, Illinois, January 7, 2014. Photo: REUTERS/Jim Young.

A man is framed by icicles as he walks along a beach in Chicago, Illinois, January 7, 2014. Photo: REUTERS/Jim Young.

A woman pushes a baby stroller through a cloud of steam from a construction site in Boston, Massachusetts January 7, 2014. Photo: REUTERS/Brian Snyder.

A woman pushes a baby stroller through a cloud of steam from a construction site in Boston, Massachusetts January 7, 2014. Photo: REUTERS/Brian Snyder.

A man wears a mask as he walks in the frigid cold temperatures in the downtown section of Manhattan, New York January 7, 2014. Photo: REUTERS/Brendan McDermid.

A man wears a mask as he walks in the frigid cold temperatures in the downtown section of Manhattan, New York January 7, 2014. Photo: REUTERS/Brendan McDermid.

A sculpture near a walking path is covered in snow in Carmel, Indiana, north of Indianapolis, January 6, 2014. Photo: REUTERS/Brent Smith.

A sculpture near a walking path is covered in snow in Carmel, Indiana, north of Indianapolis, January 6, 2014. Photo: REUTERS/Brent Smith.

Dan Devine shovels snow away so he can get his vehicle out near his home in Indianapolis, Indiana, January 7, 2014. Photo: REUTERS/Brent Smith

Dan Devine shovels snow away so he can get his vehicle out near his home in Indianapolis, Indiana, January 7, 2014. Photo: REUTERS/Brent Smith

Kim Rogers loads firewood into a wheelbarrow at her home in Indianapolis, Indiana, January 7, 2014. Photo: REUTERS/Brent Smith.

Kim Rogers loads firewood into a wheelbarrow at her home in Indianapolis, Indiana, January 7, 2014. Photo: REUTERS/Brent Smith.

Ice crystals form on a window at the U.S. Capitol in Washington, January 7, 2014. Photo: REUTERS/Jonathan Ernst.

Ice crystals form on a window at the U.S. Capitol in Washington, January 7, 2014. Photo: REUTERS/Jonathan Ernst.

A National Oceanic and Atmospheric Administration image taken from space on January 3, 2014 by the Suomi NPP satellite shows a blanket of snow that stretches from the midwestern region of the United States across to New England after a massive winter storm moved over the region. Photo: NASA/NOAA via Reuters.

A National Oceanic and Atmospheric Administration image taken from space on January 3, 2014 by the Suomi NPP satellite shows a blanket of snow that stretches from the midwestern region of the United States across to New England after a massive winter storm moved over the region. Photo: NASA/NOAA via Reuters.

Keteria Neal passes by a fountain that has frozen over in downtown Atlanta, Georgia January 7, 2014. Photo: REUTERS/Chris Aluka Berry.

Keteria Neal passes by a fountain that has frozen over in downtown Atlanta, Georgia January 7, 2014. Photo: REUTERS/Chris Aluka Berry.

A blast of Arctic air gripped the vast middle of the United States this week bringing the coldest temperatures felt in two decades, causing at least four deaths, forcing businesses and schools to close and canceling thousands of flights.