Summer in New York is a season of outdoor festivals, and although summer is mostly over, one arts festival continues to the end of September. The River to River Festival was founded in 2001 to lift the downtown economy following the 9/11 terrorist attacks. The name refers to the Hudson and East Rivers that meet at the lower tip of Manhattan, an area that encompasses Wall Street, Battery Park, City Hall, the former site of the World Trade Center, and the South Street Seaport.

This year's River to River Festival kicked off outside the New York Stock Exchange with a performance by dancers from the Martha Graham Dance Company.

Valerie Lewis, who runs the festival for the Alliance for Downtown New York, says it began when business and civic groups in lower Manhattan came together after 9/11 to revive the area.

“We banded together with our title sponsor, American Express, and said how can we a), work to really heal this community and b), how do we get people to come back downtown? How do you tell people that all of lower Manhattan hasn't been destroyed? Because people were still afraid to come to lower Manhattan, they still didn't know that you could even get downtown."

Six years later, those fears have vanished, while the festival continues to attract thousands with its free cultural programs, including theatrical performances and movie nights, museum shows, walking tours and readings. But music and dance  are still the mainstays. Jazz singer Paula West's concert was one highlight this year, organizers said. The California-based singer sang a mix of pop and jazz standards to a packed auditorium at Stuyvesant High School.

"One of the things we try to do is we try to introduce new artists to new audiences, and new audiences to new artists, even if they're just new to them,” organizer Valerie Lewis said. “And we're trying to build audiences not only for the lower Manhattan cultural scene, but New York City as a whole."

New York artists featured at the festival included Animal Collective, an experimental rock band. It played to a huge crowd at the South Street Seaport, one of the festival's main venues, located next to tall sailing ships anchored in the East River.

Valerie Lewis notes that although all events are free, festival visitors do spend in lower Manhattan’s restaurants and stores, bringing in $35 million annually to the area. This year's River to River Festival concludes with a public swim in the Hudson River, and a bicycle parade for children.