As thousands of film enthusiasts flood Lower Manhattan to attend the Tribeca Film Festival over the next 11 days, the city’s restaurants, hotels, and shops are expected to benefit from the crush of attendees.

Now firmly established as one of the top film events in America, the festival last year generated close to $120 million in economic activity for the city and has brought it about $325 million since 2002, when Robert De Niro, Jane Rosenthal, and Craig Hatkoff launched the festival as a way to revitalize Lower Manhattan in the wake of the September 11, 2001, attacks.

“It has helped reaffirm what we always thought Lower Manhattan could be,” Mayor Bloomberg said yesterday during the festival’s kick-off ceremony, attended by Vice President Gore, Rob Reiner, and Ms. Rosenthal. “Not just a global center for business, but an exciting, dynamic 24-hour cultural and residential community as well.”

The festival, which is privately run, does not release its budget. A story in the Hollywood Reporter on Tuesday said an insider claimed the event now costs $13 million, 20% of which is provided by the festival’s founding sponsor, American Express. The festival operates at a $1 million annual deficit, filled with personal contributions from the three founders, according to the report.

The Lower Manhattan Development Corporation gave the festival $3 million over two years, beginning in 2004. In 2006, the corporation awarded $600,000 to the Tribeca Film Institute to be used in the festival.

In 2005, festival attendance rose to 465,000, up 69% from the previous year, which attracted 275,000 attendees over 13 days, according to figures provided by organizers to the city. This year, 245 feature and short films will be screened at several Manhattan venues.

Nine short films about the environment, commissioned by the SOS campaign involved with this summer’s Live Earth global concert, were featured on opening night. Mr. Bloomberg, who recently unveiled an ambitious environmental plan for the city with 127 separate initiatives designed to reduce the city’s greenhouse gas emissions by 30% over the next 25 years, said he is pleased the festival is confronting environmental issues this year.

He praised the festival for highlighting “just how great a town this is for making movies,” he said, helping the city to compete for film and television productions. A tax credit program for filmmakers has brought in more than $2.4 billion in new business, Mr. Bloomberg said.