The Chicago skyline is seen beyond the arctic sea smoke rising off Lake Michigan in Chicago
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'Life threatening' freeze heads east

North America's brutal cold snap is heading east, ushering in dangerous temperatures not seen in two decades, forecasters warn.

North America's brutal cold snap is heading east, ushering in dangerous temperatures not seen in two decades, forecasters warn.

From Montana to Maryland, about half of the US population has been placed under a wind chill warning or advisory.

Beth McLeod reports from Washington.