WASHINGTON - LEADING US newspapers said on Wednesday they had been forced to fire up their printing presses again to keep pace with demand as consumers sought out mementos of Mr Barack Obama's historic election.

In the capital, about 400 people formed a queue in front of the office of The Washington Post to buy the newspaper after copies sold out across the city early in the morning.

The Post, which increased its normal print run by 30 per cent, said it had decided to produce an extra 250,000 copies of a special commemorative edition.

'I have a two-year-old grandchild and I'm going to keep a copy for her,' said Mr Vernon Short, a 68-year-old retired military man, as he waited in the queue for the special edition.

'This is a once-in-a-lifetime thing and I want to have a reminder,' he told wires agencies.

The New York Times said it had had increased its normal morning print run by 35 per cent but said it had gone back to press to produce another 75,000 copies.

At the imposing headquarters of the Chicago Tribune, a long line of people snaked out of the lobby and around the block to get their hands on its commemorative edition.

The paper restarted its presses in the morning after the initial print run of 690,000 copies sold out in the early hours.

The Tribune's vice-president of operations, Ms Becky Brubaker, said the second run would number up to 120,000 papers.

Ms Francine Garner, 48, was at the front of the queue at The Washington Times headquarters and had been waiting three hours for the commemorative edition to go on sale.

'It's about keeping track of history and having something you can keep forever,' she said.

Ms Rima Calderon, head of communications for The Washington Post, said the events of Wednesday proved the popularity of papers in an age when many are predicting their demise in the face of online competition.

'It does say something really marvellous about the printed newspaper. When there's a historic event like last night people want a printed copy for posterity,' she said.

'We didn't realise that the demand would be so large.'

The Chicago Sun-Times said it had printed extra 'tens of thousands' of copies but had also been forced back to press.

'To meet the seemingly unending demand, several thousand extra copies are being printed,' it said in an online message.

Newspapers were not the only news source in demand as CNN.com and other online news sites reported record traffic on Tuesday.

CNN.com said it received the largest daily audience in its history on Tuesday with 30 million unique visitors, more than double the previous record of 13.4 million unique visitors during the Democratic primaries on Super Tuesday.

US newspapers have been struggling in recent years with steady declines in circulation and a loss of readership and advertising to online media. -- AFP