This year, however, many Americans will be turning their thoughts on more recent victims: the estimated 1 million left homeless and many feared killed by the hurricane that wrecked the U.S. Gulf Coast nearly two weeks ago.
Both disasters served to highlight the vulnerability of the United States. But where the 11 September 2001 attacks forged a sense of national unity out of the tragedy, Katrina highlighted social problems and triggered accusations of government incompetence.
Today will be Bush's third visit to the hurricane zone since Katrina hit in August. He's supposed to attend memorial services for 11 September victims in Washington before visiting the hurricane-hit state of Mississippi.
Speaking yesterday under criticism for the slow official response to Katrina, Bush invoked the national spirit of post- 9/11 resilience in an effort to pull the nation together in the hurricane's wake. He compared the 11 September 2001 attacks to the destruction caused by the hurricane.
"Today America is confronting another disaster that has caused destruction and a loss of life. This time the devastation resulted not from the malice of evil men but from the fury of water and wind. Hurricane Katrina flattened entire towns along our Gulf Coast," Bush said.
The international relief effort for Hurricane Katrina is expected to continue for months. The number of confirmed deaths is nearly 400 across the region, giving hope that initial fears that thousands were killed may not be true.
Yesterday, Bush said Americans remember the fears, uncertainty, and confusion of the morning of 11 September. The World Trade Center's twin towers collapsed that morning after terrorists steered hijacked passenger jets into them. A third hijacked plane slammed into the Pentagon, and the fourth, apparently headed for Washington, crashed in the state of Pennsylvania. Nearly 3,000 people were killed in the attacks.
The attacks triggered the U.S.-led invasion of Afghanistan, leading to the ouster of the Taliban regime. The Taliban had been harbouring Al-Qaeda leader Osama Bin Laden.
In Afghanistan, where U.S. and Afghan troops continue to battle Taliban remnants and other Islamic militants on a regular basis, U.S. forces marked the anniversary at ceremonies held at Bagram air base, near the Afghan capital Kabul.
"We are supported and joined in this war against terrorism by a coalition of nations and by the host nation of Afghanistan, working together to defeat terrorists, shape peace, and create a better tomorrow," said U.S. Colonel Joice Stevens in leading the ceremonies.
The U.S.-led invasion of Iraq was also launched as part of the war on terrorism.
Bush evoked his determination to win the war on terror during a White House ceremony on 9 September for the firefighters and police that died on 9/11. Bush has said that the war on terror will take a long time.
Four Years Ago, 9/11 Terrorist Attacks Shook America (Part 1)
Four Years After 9/11, A Father Tries To Keep Son’s Memory Alive (Part 2)
Four Years After 9/11, New York Struggles With How To Rebuild Skyline (Part 3)