The attacks of 9/11 resulted in feelings of dislocation and disorientation for the American public at large. A focal point of American society had suddenly vanished from the New York skyline, and the country was overwhelmed by fear and disquiet. Delillo's two main characters in Falling Man, Keith and his estranged wife, Lianne, illustrate the effects of the tragedy.
After Keith's escape from the falling towers, he neither returns to his home nor seeks medical assistance. Rather, he stumbles, disoriented and wounded, through the streets of Manhattan, seeking out Lianne's apartment. His actions are both irrational and symbolic of the un-anchoring from past certainties experienced by the nation as a whole. He never returns to his former way of life. In this way, he echoes the sense of many Americans that things had changed forever on that day.
Lianne also reacts in ways she wouldn't have before the events of 9/11. She suffers a panic attack and flees through the streets until she can run no farther. She also reacts with uncharacteristic harshness when she discovers that her son has incorporated the terrorist he calls Bill Lawton into his play.
America did change that day, and the effects linger in both domestic and foreign policy. There seems to be no end to 9/11, just as Delillo depicts the plunge of the Falling Man as never-ending.