When Amir describes America as “a river,” he means that it is “unmindful of the past” (Kite Runner 136).  This particular aspect of America attracts him because in such a country he may be able to forget his own past.  He wishes that his painful memories would at least remain dormant.  If they would simply stay asleep, he could move on, forget his past decisions and become a happier person.  America’s forgetful culture could help him be happy.  If only it were that simple.