"It is not business as usual," said George Bush, in what must be the understatement of the year, as America struggled to regain the normal rhythms of a life that may never be the same after Tuesday's horrific and unprecedented terrorist attack.
In Washington, the White House and major government departments made a point of being open. But downtown streets were half empty, the normally busy skies were clear apart from military planes and police helicopters, and during the night army vehicles rumbled through districts containing sensitive federal buildings and foreign embassies.
But the US capital was a picture of normality compared with devastated New York, as rescuers struggled to rescue survivors from the debris of the two World Trade Centre towers in scenes that some likened to "nuclear winter".
The usually teeming Manhattan was deserted and thoroughfares like Sixth Avenue were populated only by cyclists – proof of how the business, media and financial capital of the US had been shut down.
Wall Street was closed for a second day. At midday, the country's airports were still shut, with no firm word when flights would resume. Originally, the authorities planned to reopen air traffic at noon, but had still not managed to put in place promised tightened security controls. The biggest US discount airline, SouthWest, said it would not restart operations until today. Logan Airport in Boston, where two of the four hijacked flights originated, said it would remain shut "indefinitely".
Norman Mineta, the Transportation Secretary, has vowed to take measures to improve passenger security, likely to include random police checks and an end to kerbside check-ins, long a traditional feature of flying in the US. He warned of higher surveillance and more stringent searches. "Travellers may experience some inconvenience but safety is our highest priority," Mr Mineta said.
Further steps are also being considered, including marshals on board every flight – a monumental undertaking given that there are 40,000 domestic flights daily in the US, with up to 5,000 planes in the air at any given moment. The realisation is growing that some loss of personal freedoms may be the price of increasing security.
Not that airline passengers, reeling from the realisation that four planes were seized in the space of an hour with minimal difficulty, will mind too much in their present mood.
The trepidation was born out in a USA Today poll showing that 87 per cent of Americans regarded the attacks as an act of war, and that nearly half would be less likely to fly in future. Four out of 10 people said they would take extra precautions in their lives – double the proportion after the 1995 Oklahoma City bombing.
Nowhere in Washington was the nervousness and despondency more evident than at the Pentagon, the giant Defence Department complex on the other side of the Potomac river.
Yesterday, smoke swirled anew from the charred hole in its south-west wing where American Airlines flight 77 tore into the structure as the fire which firefighters thought they had under control began to spread again. For the second successive day, the building was evacuated, and nerves remained on a razor's edge.
The death toll at the Pentagon is estimated at between 100 and 800. As anxious relatives waited for news of their loved ones, a policeman suddenly began yelling on a megaphone, "Get out of the area get out of the area, incoming plane" – only to reverse the instruction a few moments later: "OK, OK its friendly."
Dominating everything was a sense of powerlessness in the face of an unseen and thus far unidentified enemy. Nothing underlined the disruption of Government more than the dispersal on Tuesday of the congressional leadership as it seemed full-scale war was being waged against the US.
The leadership was taken to an underground bunker 75 miles west of Washington where they watched events unfold on television. Yesterday, House and Senate were back at work with a ringing bipartisan condemnation of the terrorist attacks. But the Capitol was ringed by extra security checkpoints, and as at the White House, the normal flow of tourists dwindled to a handful.
From some parts of the country came reports of emergency food buying. In one Oklahoma city, petrol prices briefly rocketed from about $1.50 to $5 a gallon, amid fears that supplies could dry up. These fears were quickly allayed by the oil companies.
Once again, sports schedules were disrupted. For the second successive day, and the first time since D-Day in 1944, major league baseball parks were locked and silent. The weekend's gridiron football programme may be cancelled too. "Football doesn't seem too important right now," said one NFL coach. The week's major golf tournaments are also being delayed. "This is a sad, sad day for America," Tiger Woods said.