CHICAGO (AP) -- Hundreds of holiday travelers spent the night in the nation's second busiest airport and some of them faced the prospect Wednesday of doing it again on Christmas Eve as airports across the country recovered from a barrage of snow and ice storms.
Conditions improved Wednesday but highways were still dangerously slippery in some areas.
More snow fell in the Midwest, where the National Weather Service said up to 4 inches was possible in Chicago. The Northwest faced more snow and sleet, with up to 20 inches possible in the Cascade range in Washington, and icy, wet weather spread over the Northeast.
At least 18 highway deaths had been blamed on the weather.
About 500 travelers had to spend the night at Chicago's O'Hare International, the nation's second busiest airport, after stormy weather canceled more than 500 flights Tuesday, said Chicago Aviation Department spokeswoman Karen Pride. Some slept on cots, some on the floor or across waiting-room seats, and at least some face the prospect of spending Christmas Eve at O'Hare.
Newlyweds Tommy and Siobhan Costello were at O'Hare on Wednesday gearing up to spend their second night stranded in an airport hotel en route to their honeymoon in San Diego. They arrived from their native Ireland on Tuesday, but the weather disruptions meant earliest flight out they could get was Thursday.
"This was supposed to be a pit stop," said Siobhan Costello, 30. "But there's nothing you can do."
At O'Hare's American Airlines terminal, Paul Fustini waited with a bag of food for his daughter Sara, who was trying to get home to Orlando, Fla. Her flight was canceled Tuesday and she finally got a flight for Thursday afternoon.
"She wishes I would have brought a toothbrush," Fustini said.
More than 100 flights were canceled at O'Hare on Wednesday. On Tuesday, cancellations totaled more than 500.
"The airlines are dealing with nothing but unhappy customers," said Mike Conway, spokesman for Detroit's Metropolitan Airport, where delays were reported in departures and arrivals because of conditions elsewhere in the country.
The weather service posted winter storm warnings and advisories for large parts of the West, plus parts of the Midwest and the Northeast.
Driving conditions were still tough in Oregon's Portland metro area, where many side streets were still clogged with snow and motorists were required to have tire chains, unless they had four-wheel drive and tires designed for hazardous weather. More snow fell in the region Wednesday.
Oregon's state's largest utility, PGE, said it had restored service to 265,000 customers since the stormy arrived Friday, but 47,000 were still blacked out Wednesday.
"The rain and sleet just hit everywhere at once, and we're encouraging everybody to reduce speed and take it easy out there," Massachusetts Trooper Thomas Murphy said.
Police in southeastern Pennsylvania reported a spate of ice-caused accidents and traffic delays, including one 22-vehicle crash. No serious injuries were reported.
Motorists in Michigan had to cope with drifting snow in places in addition to ice-covered pavement.
"It looks like all areas should see a white Christmas," meteorologist Dave Kook said from the weather service office in Oakland County's White Lake Township. "There's enough snow on the ground that it won't all melt away with the rain."
Despite more snow falling Wednesday in the Seattle area, operations at Sea-Tac Airport were back to normal Wednesday, said spokeswoman Terri-Ann Betancourt. She said the last of thousands of passengers who were stranded by weekend cancellations were gone by Tuesday, and the only flight cancellations were caused by delays or cancellations at other airports.
"I've lived here 16 years and this is the first time I've thought 'I wish it would rain!'" Betancourt said.
The weather service said she could get her wish, at least briefly, with snow showers changing to rain Christmas Eve.
Amtrak also reported improvement Wednesday. Trains out of Chicago and elsewhere were leaving on time - or relatively close to it - unlike Tuesday when several trains were canceled and some 600 furious travelers waited for as much as 22 hours for delayed trains at Chicago's Union Station, spokesman Marc Magliari said.
At least 18 people were killed in crashes on rain and ice-slickened roads Tuesday and Wednesday - four each in Indiana and Kentucky, two in Missouri, two in Kansas, two in Wisconsin, one in Oklahoma, one in Ohio, one in Iowa, and a state lawmaker was killed in West Virginia.