LAS VEGAS: A massive winter storm set the stage for a brutal travel day Sunday, with airlines warning of widespread cancelations and delays at some of the nation’s busiest airports. Widespread snow, sleet and freezing rain threatened nearly 180 million people — more than half the US population — in a path stretching from the southern Rocky Mountains to New England, the National Weather Service said Saturday night.

U.S. airlines canceled flights and waived change fees for travelers as a cold snap and massive winter storm were forecast to sweep across the country.

Impacts from what could be the most significant storm of winter are expected to begin on Friday, spreading ice, snow and cold across much of the U.S.