OKLAHOMA CITY (AP) — Thousands of flights across the U.S. set to take off over the weekend were canceled as a monster storm started to wreak havoc Saturday across much of the country, knocking out power and snarling major roadways with dangerous ice.

Widespread heavy snow, sleet and freezing rain threatened nearly 180 million people — more than half the U.S. population — in a path stretching from the southern Rocky Mountains to New England, the ɫtv Weather Service said Saturday night. It warned people to brace for a string of frigid days.

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