President Barack Obama smiles as he walks from Air Force One to an awaiting Marine One helicopter at Detroit Metropolitan Airport, Saturday, May 1, 2010, in Romulus, Mich. President Obama is visiting Ann Arbor, Mich. to give the commencement address at the University of Michigan's football stadium, the first sitting U.S. President at the Big House since George H. W. Bush in 1991. (AP Photo/Tony Ding)