Forecasters have warned that snow and ice could thwart millions of people hoping to get home after Thanksgiving.
The storm has already shut down highways, stranding drivers in California and prompting authorities in Arizona to plead with travelers to wait out the weather.
The storm is expected to track east through the weekend - into the plains on Friday, the Midwest by Saturday and the Northeast on Sunday - pummeling the country with snow, ice or flash flooding.
The National Weather Service alerted that travel could become impossible in some places.
The weather could become particularly disruptive Sunday, when the airline industry’s trade group expects 3.1 million passengers on what could be the busiest day ever recorded.