A Marine salutes as motorcyclists ride past during Rolling Thunder 2012 in Washington, DC, on May 27, 2012. Rolling Thunder was first held in 1988 when a group of bikers, all of them Vietnam veterans,... more 

A Marine salutes as motorcyclists ride past during Rolling Thunder 2012 in Washington, DC, on May 27, 2012. Rolling Thunder was first held in 1988 when a group of bikers, all of them Vietnam veterans, decided to ride in Washington every year on or about the Memorial Day holiday to demand the return of remains of POWs and those missing in action (MIAs) less