Snow and ice storms across the United States have made it difficult for holiday travelers to reach their destinations.

Many people were stranded overnight at the main O'Hare airport in Chicago, in the midwestern state of Illinois Tuesday and Wednesday, after airlines canceled hundreds of flights due to snowy conditions.

Adding to the trouble, an American Airlines plane at the Chicago airport slid off the runway late Wednesday after hitting an icy patch. Officials say no one was injured.

U.S. Airways plane taxis past snow removal trucks working to clear snow at  Seattle-Tacoma International Airport in Seattle, Washington, 22 Dec 2008

On the other side of the country, severe winter weather forced the governor of the northwestern U.S. state of Washington to declare a state of emergency on Wednesday.

The governor said snowfall has reached record or near-record levels in 30 of Washington's 39 counties. She said many areas in the state are expecting more than 30 centimeters (one foot) of additional snow later this week.

The weather has also made road travel difficult. Slick and snowy conditions have led to a number of fatal car accidents across the United States.

The storms also hurt train and bus travel, and delayed flights at airports in the eastern states of New York and New Jersey and the western states of California and Washington.

Some information for this report was provided by AP.