The extravaganza in Manhattan is the first of the four major shows for pret-a-porter 2010 spring-summer collections, ahead of Milan, Paris and London.
A hundred or so designers, including Ralph Lauren, Marc Jacobs, Diane von Furstenberg and Philip Lim, will unveil collections in the session lasting until September 15 at Bryant Park and in a scattering of other halls and museums.
The events provide a rallying point for a global industry that has been pummeled by the store closings, advertising cuts, and disappearance of consumers over the last year.
New York Mayor Michael Bloomberg gave an additional boost announcing the city will lead, also on Thursday, a worldwide Fashion's Night Out, when more than 700 stores will stay open late and offer entertainment.
Although fashion may seem a distant, even haughty world to humble consumers, industry bigwigs like American Vogue editor Anna Wintour and rapper Sean Combs, known as Diddy, are keen to emphasize its importance.
Just in New York, 175,000 people are employed in fashion-related jobs, with the sector generating some 10 billion dollars, they tell a promotional video ahead of Thursday's event.
To underline that populist message, they and other luminaries like Diane von Furstenberg appear in the video wearing black and white T-shirts which will be on sale Thursday, with 40 per cent of the proceeds going to the 9/11 memorial.
There has been nothing but bad news for fashion over the last year, a litany of store closings, buyouts, firings, and predictions that consumers may never recover their old spendthrift ways.
So far, there is little sign that the new season is bringing big change.