The Tribeca Film Festival is giving to the downtown Gotham nabe that birthed it to its opening night event, with a world preem screening of new Cameron Crowe documentary “The Union” to be held free of charge outdoors on the fest’s first day, April 20.

be on hand to perform live following the Tribeca preem.

Fest, founded in response to the economic hardships that hit downtown New York in the wake of the Sept. 11 terrorist attacks, has always made a point of playing up its connections to the community. Last year Tribeca incorporated outdoor screenings of films including “The Spirit of Salsa” and “Big.”

Crowe, whose is also working on a Pearl Jam documentary, began shooting the “Union” doc in late 2009 to follow the collaboration between John, Russell and producer T-Bone Burnett. Film incorporates appearances by fellow album contributors including Neil Young, Brian Wilson, Booker T. Jones and lyricist Bernie Taupin.

Pic will screen at the North Cove in the World Financial Plaza.

Full sked for the 2011 outing of Tribeca, which runs through May 1, will be announced over the next two weeks.