(CNN) -- First lady Michelle Obama will join former first lady Laura Bush on September 11 at the Flight 93 National Memorial outside Shanksville, Pennsylvania, according to a statement from the National Park Foundation.
Obama and Bush will be joined by Interior Secretary Ken Salazar and Pennsylvania Gov. Ed Rendell.
"Their show of support honors the lives and memories" of the 40 passengers and crew on the flight, along with "everyone we lost on September 11, and serves as a valuable reminder of how important this memorial is to preserve and share their story," said Neil Mulholland, head of the foundation.
United Flight 93 crashed into a field near Shanksville after the passengers and crew fought back against hijackers who had seized control of the plane.
Fundraising is now under way for a memorial slated for dedication on September 11, 2011, the statement noted.
CNN's Paul Courson contributed to this report