Vice President Joe Biden, left, and Interior Secretary Ken Salazar arrive at the Flight 93 National Memorial in Shanksville, Pa., for a memorial service, Tuesday, Sept. 11, 2012. (AP Ph

 

              Vice President Joe Biden, left, and Interior Secretary Ken Salazar arrive at the Flight 93 National Memorial in Shanksville, Pa., for a memorial service, Tuesday, Sept. 11, 2012. (AP Ph
Vice President Joe Biden, left, and Interior Secretary Ken Salazar arrive at the Flight 93 National Memorial in Shanksville, Pa., for a memorial service, Tuesday, Sept. 11, 2012. (AP Photo/Gene J. Puskar)