Even while maintaining its status as one of the few musical acts that can still fill stadiums, U2 is struck by how quickly its world is changing — musically and politically.

Charismatic front man Bono, in a reflective mood as U2 closes the North American leg of its "360" tour, notes the different, more polarized atmosphere in the United States since the band performed its anthem, "City of Blinding Lights," at President Obama’s inauguration in January.