By Stephen Evans BBC North America business correspondent

New York has changed in lots of significant though often quiet, barely perceptible ways.

Many New Yorkers will tell you that the streets are quieter than they were, courtesy has become more obvious, and there isn't the rush to honk the car horn like there was.

Some people who were caught up in the World Trade Center on the day have become quieter and more thoughtful.

Some will keep away from the commemoration, choosing instead to get out of the city.

Immediately after 11 September, the Stars and Stripes became a symbol of democracy.

New Yorkers continue to be afraid, particularly on the subway, the underground railway.

There is a presumption among many that another attack will happen, and unlike in other cities with other groups like the IRA, the aim will be to kill as many people as possible without warning.

Souvenir sellers

It has to be said that there is also a tacky, ghoulish aftermath.

The area around Ground Zero is crowded with souvenir sellers, vendors offering T-shirts and baseball caps to commemorate the visit to the tourist site, it seems to me, rather than the event a year ago.

Judging visitors to sites of tragedy is difficult. Do people come to pay respect and to reflect, or do they come to gawp and say they have been there.

The last beam of the World Trade Center is removed

I always take people down there when they visit, but feel uneasy if they start taking pictures.

There is some rancour, particularly among firefighters who feel they have been taken for granted.

A month ago, they demonstrated for more pay, with the general theme that they were sick of politicians praising them but refusing to pay them.

Stars and Stripes

The meaning of the flag has changed in the past year. Immediately after 11 September, the Stars and Stripes became a symbol of democracy.

It ceased to be just the flag of a nation - a jingoistic symbol, perhaps - and became a symbol with a wider appeal.

People wore the flag, say on jerseys or shirts or lapel pins - as a mark of opposition to a profoundly undemocratic act (you don't get much further from democracy than you do if you kill innocent people to make a point).

I talked to people on the Left who felt the flag belonged to them again for the first time since before the Vietnam War.

I think the flag has been snatched back now. It does not quite mean what it did before, but you do detect a sense that it is a symbol of America against the world. The country feels embattled.

Everyone wears the flag, but it seems to me, that it has become again a symbol of nationalism rather than of a just international cause.