25 years after 9/11, America still lives in the world the attacks remade

At 8:46 a.m. on Sept. 11, 2001, American Airlines Flight 11 struck the North Tower of the World Trade Center in New York.

Seventeen minutes later, United Airlines Flight 175 hit the South Tower. American Airlines Flight 77 struck the Pentagon outside Washington less than an hour after the first attack, and United Airlines Flight 93 crashed into a field near Shanksville, Pennsylvania, after passengers and crew fought back against the hijackers.

By the end of the morning, both towers were gone. The Pentagon was burning. A field in rural Pennsylvania had become a crime scene. A total of 2,977 people had been killed in the attacks, including 343 New York City firefighters, 37 Port Authority police officers and 23 New York City police officers. The physical destruction was concentrated in three places. What followed wasn’t.

Twenty-five years later, the effects of Sept. 11 can still be found almost everywhere in American life, from airport security checkpoints and intelligence agencies to the wars the country fought, the surveillance powers it granted its government and the way a generation of Americans came to understand national security.

It also reshaped the world beyond U.S. borders. Alliances were activated, governments rewrote counterterrorism laws, intelligence services expanded their reach and American forces were sent into conflicts and operations stretching from Afghanistan and Iraq to Africa, the Middle East and elsewhere.

Domestic Surveillance & Shifting Views

For Americans old enough to remember the attacks, Sept. 11 remains unusually personal. A Pew Research Center survey released ahead of the 25th anniversary found that 83% of adults born before 2001 remember exactly where they were or what they were doing when they first heard the news. Among those who were at least 10 years old at the time, that figure rises to 93%.

But the country remembering 9/11 in 2026 is increasingly different from the one that experienced it. About 100 million Americans are now too young to remember the attacks, according to the National September 11 Memorial & Museum. Millions more weren’t alive at all. For them, 9/11 isn’t a memory of television broadcasts, smoke over Manhattan, or parents leaving work early. It’s history learned in classrooms, documentaries, and stories told by people who were there.

That generational shift comes as many of the institutions created in response to the attacks have become so routine that it’s easy to forget they didn’t exist before them. The Transportation Security Administration was created in November 2001, shifting responsibility for airport passenger screening to the federal government. Reinforced cockpit doors, expanded baggage screening, watch lists and a far more intensive aviation security system followed.

The Department of Homeland Security began operating in 2003, combining 22 agencies and offices under a single Cabinet department. The government later created the Office of the Director of National Intelligence and the National Counterterrorism Center, largely in response to one of the central findings of the 9/11 Commission: U.S. agencies had information about the threat before the attacks but repeatedly failed to share, connect and act on it.

The phrase “connect the dots” became part of the national security vocabulary. So did a new emphasis on prevention.

The USA PATRIOT Act, signed into law six weeks after the attacks, broadened investigative and surveillance authorities and made it easier for intelligence and law enforcement agencies to share information. Some of its provisions were later modified or allowed to expire, particularly as disclosures about government surveillance fueled a yearslong debate over the balance between security and privacy. That debate never really ended. Neither did the legal framework for the war that followed.

The Global War on Terror

On Sept. 18, 2001, Congress authorized the president to use military force against those responsible for the attacks and those who harbored them. The authorization contained no expiration date. Twenty-five years later, it remains in effect, even after the separate authorizations for the 1991 Gulf War and 2003 Iraq War were repealed.

The first and most direct military response came in Afghanistan. U.S. and allied forces began operations there in October 2001, targeting al-Qaida and the Taliban government that had sheltered Osama bin Laden and his organization. The Taliban government quickly fell, but the war didn’t end with it. The United States would remain in Afghanistan for nearly 20 years.

Bin Laden was killed by U.S. forces in Pakistan in 2011, almost a decade after the attacks. Al-Qaida’s ability to organize another attack on the scale of Sept. 11 was badly degraded. But the conflict in Afghanistan continued for another decade as the Taliban rebuilt an insurgency and successive U.S. administrations struggled with what victory was supposed to look like.

The final American troops left Afghanistan in August 2021. The Taliban had returned to power before the withdrawal was complete. But by then, the post-9/11 wars had extended far beyond Afghanistan.

The United States invaded Iraq in 2003 amid the broader security environment created by 9/11, although Iraq wasn’t responsible for the attacks. The war toppled Saddam Hussein but helped unleash years of insurgency and sectarian violence. Al-Qaida in Iraq emerged from the conflict and eventually helped give rise to the Islamic State group, which seized large areas of Iraq and Syria in 2014 and triggered another U.S.-led military campaign.

Counterterrorism operations, drone strikes, special operations missions and military partnerships spread across multiple continents. NATO also changed. On Sept. 12, 2001, the alliance moved to invoke Article 5, its collective defense provision, for the first and, so far, only time in its history. The principle that an attack against one member would be treated as an attack against all had been written to deter states during the Cold War. Its first use came in response to a terrorist organization.

The Cost of War

The costs accumulated over two decades. Brown University’s Costs of War project estimates the United States has spent or obligated about $8 trillion on the post-9/11 wars, including military operations, homeland security, interest and long-term care for veterans. The project estimates at least 940,000 people have died directly from violence in the post-9/11 war zones and about 38 million have been displaced.

Those figures stretch far beyond the original battlefields of Afghanistan and Iraq and include civilians, combatants, aid workers, journalists and others across a series of conflicts shaped in different ways by the post-9/11 era.

The costs also continue at home. Firefighters, police officers, construction workers, residents, office workers and others exposed to dust and contaminants around the World Trade Center developed cancers, respiratory illnesses and other conditions in the years after the towers fell. The federal World Trade Center Health Program now serves nearly 150,000 responders and survivors across all 50 states and U.S. territories. For them, Sept. 11 didn’t end when the smoke cleared.

Islamophobia after 9/11

The attacks left another complicated legacy for Muslim Americans. In the days after 9/11, President George W. Bush publicly urged Americans not to equate Islam with terrorism. But anti-Muslim hate crimes surged, and suspicion toward Muslims became a recurring part of American political and cultural life.

Twenty-five years later, Pew found that 59% of Muslim Americans say there is “a lot” of discrimination against Muslims in the United States. Another 2026 survey found 43% of U.S. adults believe Muslims are less patriotic than other Americans.

At the same time, the Muslim American population has more than doubled from Pew’s first estimate in 2007, and Muslim Americans have gained greater visibility in business, government and elected office.

Looking Forward

The country has changed in other ways that would have been difficult to imagine in 2001. The terrorist threat that drove U.S. national security policy for much of the early 21st century is no longer the only threat demanding Washington’s attention. Competition with China, Russia’s confrontation with the West, cyberattacks, disinformation, nuclear proliferation and renewed interstate warfare now occupy much of the national security agenda.

Terrorism hasn’t disappeared. The U.S. intelligence community said in its 2026 Annual Threat Assessment that setbacks have made groups such as al-Qaida and the Islamic State less capable of carrying out the kind of large, centrally directed operation seen on Sept. 11. Instead, terrorist organizations increasingly use propaganda and online networks to inspire or enable individuals who already live in the West. In other words, the threat changed along with the defenses built to stop it.

There hasn’t been another terrorist attack on American soil approaching the scale of Sept. 11. The elaborate overseas network that planned the attacks was hunted for years, its leadership decimated and its ability to operate openly in many places sharply constrained. That is one measure of success. But 25 years of hindsight makes the rest of the record harder to summarize.

The United States destroyed al-Qaida’s sanctuary in Afghanistan, only to leave two decades later with the Taliban back in Kabul. It built an enormous counterterrorism and intelligence apparatus that closed many of the gaps exposed by 9/11, while opening new arguments about surveillance, executive power and civil liberties.

It fought wars meant to make the country safer, while some of those wars created instability and armed groups of their own. It experienced a rare moment of national unity after the attacks, then returned to political division that grew deeper over the decades that followed. And the country spent trillions of dollars and lost thousands of service members in conflicts whose consequences are still being calculated.

For much of the generation that remembers Sept. 11, the world before that morning can feel like a different era. Airport gates could be reached without a boarding pass. The Department of Homeland Security didn’t exist. The United States wasn’t fighting a global campaign against terrorism. Afghanistan was a distant country that rarely appeared in American headlines.

For the generation that came afterward, the opposite is true. The security checkpoints, intelligence bureaucracy, distant military operations and constant awareness of terrorism have always been there. That may be the clearest measure of how completely Sept. 11 changed the country.

Twenty-five years later, the towers are no longer part of New York’s skyline. The war in Afghanistan is over. Osama bin Laden is dead. The organization he led is a fraction of what it was when 19 hijackers boarded four airplanes on a Tuesday morning in 2001.

But America is still living in the world they helped create.