Nearly 7.5 inches (19 centimetres) of snow was reported at Chicago's O'Hare International Airport before the front moved out of the area on Friday.

About 500 flights were cancelled at O'Hare, which canceled 600 flights Thursday and housed hundreds of stranded travelers who spent the night awaiting planes from other cities also affected by the storm.

At least 12 inches (30 centimetres) of snow was reported in Springfield by Friday morning, said National Weather Service meteorologist Gino Izzi. Other parts of Illinois saw similar amounts.

'If you don't have to be out here, don't,' Ty Wilson, a very wet Chicago bicycle messenger, said as he stopped along a slushy street between morning deliveries.

The storm brought snow, freezing rain and sleet to the Northeast, where arriving flights at Newark Liberty Airport were delayed as long as three hours on Friday afternoon.

Arrivals were delayed by two hours at La Guardia Airport, two hours at Philadelphia International and an hour and a half at New York's Kennedy, according to the Federal Aviation Administration's Web site.

At least four people died on Friday on ice-slicked New York state roads. Six people died on Illinois roads on Thursday and Friday.

Another storm system made roads impassible in parts of the Pacific Northwest.

In Washington state, a 70-mile stretch of Interstate 90 remained closed because of the avalanche danger at the Snoqualmie Pass in the Cascade Range.

Two Amtrak passenger trains carrying 400 people got stuck in the mountains of Northern California near Donner Pass, agency officials said. No injuries were reported.

The trains had been stuck since 2 pm (2am Singapore time) on Friday, but the passengers are being fed and both trains have heating and lights, Amtrak spokeswoman Karina Romero said.

The tracks were expected to be cleared early Saturday morning. -- AP