(NBC News) A deep freeze gripped almost the entire United States on Friday pushing temperatures to 20 below in Wyoming, emptying stores in Texas of firewood and threatening to knock out power across an ice-glazed swath of the South and Midwest.
In north Texas alone, more than 600 flights were canceled and an estimated 250,000 people were left in the dark as sleet weighed down power lines and snapped tree branches.
Dallas called off its marathon for this weekend, with many of the thousands of expected runners unable to get there.
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