The western United States is bearing the brunt of new winter storms, with heavy snow blanketing an area from New Mexico to Minnesota.
Snow and ice have closed a number of major roads, with Arizona and New Mexico particularly badly hit.
Denver, Colorado, had its heaviest snowfall of the season.
Wild weather is also hitting southern states - three people are reported dead after an unseasonal tornado struck Arkansas.
Ice and snow forced the temporary closure of Interstates 40 and 17 in northern Arizona, with a traffic hotline in the state taking more than a million calls on Thursday.
Phoenix was braced for rare freezing temperatures. Residents are astonished by the sight of snow flurries in the usually temperate southwestern capital.
Many drivers were stranded near the Grand Canyon as all the lanes of Interstate 17 were closed overnight.
In Colorado, the Silverton Mountain resort reported huge snowfall and closures for avalanche control.
Denver was expecting up to 1ft (30cm) of snow on New Years Eve - United Airlines cancelled 32 flights from the city on Thursday.
Wyoming, Montana and Nevada suffered serious road closures, while a sudden blizzard combined with winds of up to 65mph (105km/h) caused havoc in southern New Mexico.
An 80 mile stretch of interstate 40 was closed in New Mexico. Authorites erected a temporary shelter for stranded travellers.
"Everything is really, really slick so we are discouraging people from travelling," Police Captain Terry Thortonberry told local media there.
Blizzards in Fargo, North Dakota, led to a pile-up of 100 vehicles, with at least two people taken to hospital.
National Weather Service forecaster Bob Oravec told AFP news agency: "We're expecting almost a one-two punch across the middle part of the country over the next two days.
"Once the large-scale pattern sets up you can be very stormy and have one after another."
A massive rockfall closed one key road into the Yosemite National Park in California.
The eastern seaboard is just recovering from a winter storm that paralysed transport, bringing an apology from New York's mayor over clean-up efforts.
New York Mayor Michael Bloomberg admitted the city's response to the recent blizzard was "inadequate and unacceptable".
"Clearly the response to this storm has not met our standard or the standard that New Yorkers have come to expect from us," he told reporters.
Snow was not cleared from large parts of New York for days after the storm.
New Yorkers appeared particularly outraged by stories of ambulances unable to come to the aid of sick residents, which led to the death of a newborn baby in one case.
At one point, 600 city buses became stuck in the snow, blocking streets, but they had all been cleared by Thursday.
New York's three airports were back to operating on regular schedules, but airlines warned that it would be some time before the backlog of stranded passengers has cleared.