It has been 22 years since the United States experienced an event that forever altered the nation’s trajectory and left an indelible mark on the American psyche.

On September 11, 2001, hijackers commandeered four commercial airliners and used them as weapons. Two of the planes crashed into the Twin Towers at the World Trade Center in New York City. The towers collapsed, killing more than 2,700 people.

A third plane hit the Pentagon, killing 125 people inside the building and all 59 passengers on board. The fourth plane, believed to have been destined for the U.S. Capitol, crashed in a Pennsylvania field after the passengers heroically attempted to take control of the plane from the hijackers.

The attack was carried out by members of the radical Islamist group Al-Qaeda. The geopolitical fallout resulted in a 20-year war in Afghanistan and more than a decade of military conflict in Iraq.

Americans were left in shock, disbelief, and mourning. In the days that followed, the nation came together in an unprecedented display of unity and resilience. Communities rallied around the victims and their families, and first responders heroically risked their lives to save others. The day has become a symbol of American resilience and unity, as well as a reminder of the fragility of U.S. security.

Memorials such as the 9/11 Memorial and Museum in New York City and the Flight 93 National Memorial in Pennsylvania stand as solemn reminders of the tragedy. Each year, on the anniversary of the attacks, Americans pause to reflect on the events of that fateful day and pay tribute to the victims and the first responders who risked their lives to save others.

“For those of us who lost people on that day, that day is still happening. Everybody else moves on. And you find a way to go forward, but that day is always happening for you,” said Edward Edelman, who was at ground zero to honor his brother-in-law, according to WFAA.

Vice President Kamala Harris, Florida Gov. Ron DeSantis, and former New York City Mayor Rudy Giuliani convened at the site on Monday. Also in attendance were Senate Majority Leader Chuck Schumer (D-NY), Sen. Kirsten Gillibrand (D-NY), New York City Mayor Eric Adams, and former New York City Mayor Michael Bloomberg, according to the Associated Press.

The names of identified victims were read aloud. More than 1,000 human remains have yet to be identified.

President Joe Biden was not in attendance, having planned to mark the anniversary in Alaska, where he will offer remarks at Joint Base Elmendorf-Richardson in Anchorage.