The United States on Friday marks the 25th anniversary of the September 11, 2001 terrorist attacks — the largest terrorist attack in the country's history. The main memorial events traditionally take place in New York City, where relatives of the victims publicly read the names of those who perished, as well as at the Pentagon, where U.S. President Donald Trump will participate in the ceremony. On September 11, 2001, terrorists from the Al-Qaeda group hijacked four passenger planes. Two of them were directed at the towers of the World Trade Center in New York City, while the third was aimed at the Pentagon building. Passengers on the fourth plane managed to resist the hijackers. The aircraft crashed in Pennsylvania, failing to reach its intended target. The specific object that the terrorists planned to attack has never been officially determined. As a result of the attacks, nearly 3,000 people died. However, a quarter of a century later, the tragedy continues to claim lives. In New York City, a separate memorial ceremony will also take place on Friday for those who have died in the years since the attacks from illnesses caused by exposure to toxic dust and other hazardous substances created after the collapse of the World Trade Center towers. The U.S. government acknowledges that the number of deaths resulting from the aftermath of the tragedy has long surpassed the number of people who died directly on September 11, 2001. According to the Centers for Disease Control and Prevention (CDC), more than 57,000 cases of cancer related to the aftermath of the attacks have been reported to date. These figures show that the impact of the events of September 11 was not limited to just one day. For thousands of rescuers, firefighters, police officers, medical personnel, and residents of New York City, the tragedy continues to have repercussions decades later. This year, the memorial events take on special significance: the 25th anniversary has become one of the largest dates in U.S. history dedicated to honoring the victims of terrorist attacks.