On September 9, 2001, the terrorist attack against the United Nations had shocked the whole country taking lives of a large number of people. The event of 9/11 had changed the perceptions of Americans about the Muslims. The event of 9/11 is one of the most influential events in the history of America, and it has gone through severe changes after this event. Its impact can be still seen in several aspects of the society in America.On the morning of 9 September, the terrorist hijacked the plane and attacked the world trade centre and pentagon that was one of the longest towers of the world at that time and integral part of the financial sector of the USA. The damage to these towers caused an ultimate collapse of the economy all over the world. Moreover, causalities that were occurred in the event were from America as well as from other countries of the world.Almost 3000 people were killed in that accident that includes passengers on the jets, hijackers, and people in the pentagon and world trade centre. Terrorists targeted the vital symbols of United States military power and Economy. The effects of this event were observed all around the world.The event of 9/11 had substantial effects on the America that include an increase in the security, having hatred feeling towards the Muslims and a negative effects on the health of people especially those residing or present near the attacks. These effects are long-lasting and somehow permanent.Now the government has put more pressure on the security in airports and other stations for people safety but deep inside most people are not going to rely on security to keep them safe. The attack on the World Trade Center has changed everyone mentally and physically.