As the nation marks the seventh anniversary of the Sept. 11 terrorist attacks, voters are considering who will take over from the administration whose tenure and policy was shaped by the destruction of the World Trade Center, the downing of a plane over Pennsylvania and the strike on the Pentagon. The attacks, which killed more than 3,000 people, continue to cast a long shadow over the nation and its politics as Americans disagree over the reason for the attacks and the appropriate response to them.

One reason for the persistent disagreement is the Bush administration’s immediate and continuing response to the attacks. The world largely rallied around the United States when it went into Afghanistan to find Osama bin Laden, the cheerleader and financier of the Sept. 11 killings, and to rout his hosts, the Taliban. Nearly seven years later, Afghanistan remains in turmoil as violence has escalated, killing hundreds of U.S. troops and thousands of civilians.

The mission in Afghanistan was largely forgotten, however, when the U.S. invaded Iraq in 2003 under the false pretenses that Saddam Hussein had a hand in the Sept. 11 attacks and was stockpiling weapons of mass destruction. Arguments over the rationale for attacking Iraq have given way to debates over if and when U.S. troops should leave the country. That debate is largely in the hands of the Iraqi government, which is negotiating an agreement with the Bush administration that will define the U.S. presence beginning next year.

Another Bush legacy of Sept. 11 are the nearly 300 men held as enemy combatants at a detention center at Guantanamo Bay, Cuba. Despite repeated Supreme Court rulings that the men cannot be held without the ability to challenge their detention, the administration has pressed ahead with a system of military tribunals. The first such tribunal found a former driver for Osama bin Laden guilty of providing support to terrorism and sentenced the man to six years in jail. Counting the time he’s been held in Gitmo, he should be released in a few months. The Bush administration said it will continue to detain him anyway.

At home, lawmakers quickly passed the Patriot Act, which gave law enforcement greater leeway in monitoring Americans who in theory could be helping terrorists. Lawmakers also largely went along with a wiretapping system that allowed government eavesdropping on phone calls without a warrant. Communications companies were given immunity from lawsuits for cooperating with the electronic spying despite constitutional privacy protections for their customers.

Terrorist networks are largely dispersed and their attacks less grandiose (if no less deadly), experts say. But the U.S. occupation of Iraq, the Israeli stranglehold on the Palestinian territories and the lawlessness of the mountainous Afghanistan-Pakistan border will breed new generations of terrorists. They are not necessarily Islamofacists, in the parlance of President Bush, but disengaged young men who see violence as the only way to show their anger and gain power, if only momentarily.

Even as economic concerns and high energy prices are at the top of the public’s agenda, seven years after Sept. 11 and just weeks before the presidential election, the attacks, and the reaction to them, remain defining moments.