PORTLAND, Ore. >> Winter storms sowed more chaos across the U.S. on Thursday, shutting down much of Oregon’s largest city with almost a foot of snow and paralyzing travel from parts of the Pacific Coast all the way to the northern Plains.

The nearly 11 inches that fell in Portland amounted to the second snowiest day in the city’s history. It took drivers by surprise, stalling traffic during the Wednesday evening rush hour and trapping motorists on freeways for hours.

Some spent the night in their vehicles or abandoned them altogether as crews struggled to clear roads. Other commuters got off spun-out buses and walked in groups to safety. The National Weather Service, which had predicted only a slim chance of significant snow, planned to review its work.

The weather also knocked out power to almost a million homes and businesses in multiple states, closed schools and grounded or delayed thousands of flights. The system even brought snow to usually balmy Southern California.

Kim Upham endured a 13-hour ordeal as snow brought to a standstill the traffic on U.S. 26, a mountainous highway that connects Portland to the coast. Already treacherous because of its steep grade, the highway was covered in a sheet of ice, forcing some drivers to leave their cars in the middle of the road.

“It was so scary to have semi-trucks behind you and semi-trucks in front of you, and you know you’re on a slope,” she said.

As the hours stretched on, some drivers began to worry about surviving until morning. Upham used a blanket to stay warm and spent the night in her car. To save gas, she turned the vehicle on only intermittently to run the windshield wipers and inch ahead when traffic moved slightly.

“I really don’t want to die on 26,” she added.

“I was thinking that quite often, to be honest with you.”

The Multnomah County medical examiner’s office said it was investigating a suspected hypothermia death related to the storm. The agency offered no details.

Amid concern for the thousands of people who live on Portland’s streets, city and county officials said they would open three additional overnight shelters Thursday evening, for a total of six. The sites would be able to sleep about 700 people.

Some reveled in the surprise day off in a place that rarely gets measurable snow.

Joan Jasper snapped on skis and was gliding through a residential neighborhood.

“They always have like ‘snowmageddon’ on the news, and so we kind of ignored it — and 11 inches later here we are!” she said. “This is gorgeous.”

In Northern California, Karen Krenis was driving to a pottery studio in Santa Cruz, when she stopped in her tracks after seeing snow on the beach. She got out of her car and went to take photos. By the time she left, about 50 other people were there. Adults were snapping photos, and children were making snowballs.

“I have lived in California for 30 years, and I’ve never seen anything like it,” Krenis said.

In Wyoming, roads across much of the southern part of the state were impassable, state officials said.

Rescuers tried to reach stranded motorists, but high winds and drifting snow created a “near-impossible situation,” said Sgt. Jeremy Beck of the Wyoming Highway Patrol.

High winds and heavy snow in the Cascade Mountains prevented search teams from reaching the bodies of three climbers killed over the weekend in an avalanche on Washington state’s Colchuck Peak.

Portland residents had expected no more than a dusting to a few inches.