Collapse of the World Trade Center

Collapse of the World Trade Center
Part of the September 11 attacks
The dust cloud following the collapse of the South Tower (left), and a view from the same position, of the collapse of the North Tower
DateSeptember 11, 2001; 23 years ago (2001-09-11)
Time9:59 a.m.[b] – 5:21 p.m. (EDT)
LocationLower Manhattan, New York City
Coordinates40°42′42″N 74°00′45″W / 40.71167°N 74.01250°W / 40.71167; -74.01250
TypeBuilding collapse
Deaths2,763[c]
Non-fatal injuriesc. 6,000–25,000[d]

The World Trade Center in Lower Manhattan, New York City, was destroyed on September 11, 2001, as a result of al-Qaeda's terror attacks. Two commercial airliners hijacked by terrorists were deliberately flown into the Twin Towers of the complex, resulting in a total progressive collapse that killed almost 3,000 people. It was the deadliest and costliest building collapse in history.

The North Tower (WTC 1) was the first building to be hit when American Airlines Flight 11 crashed into it at 8:46 a.m.,[a] causing it to collapse at 10:28[e] after burning for one hour and 42 minutes.[f] At 9:03 a.m.,[g] the South Tower (WTC 2) was struck by United Airlines Flight 175; it collapsed at 9:59 a.m.[h] after burning for 56 minutes.

The towers' destruction caused major devastation throughout Lower Manhattan, and more than a dozen adjacent and nearby structures were damaged or destroyed by debris from the plane impacts or the collapses. Four of the five remaining World Trade Center structures were immediately crushed or damaged beyond repair as the towers fell, while 7 World Trade Center remained standing for another six hours until fires ignited by raining debris from the North Tower brought it down at 5:21 that afternoon.

The hijackings, crashes, fires and subsequent collapses killed an initial total of 2,760 people. Toxic powder from the destroyed high-rises was dispersed throughout the city and gave rise to numerous long-term health effects that continue to plague many who were in the towers' vicinity, with at least three additional deaths reported.[17] The 110-story towers are the tallest freestanding structures ever to be destroyed, and the death toll from the attack on the North Tower represents the deadliest terrorist act in world history.[i]

In 2005, the National Institute of Standards and Technology (NIST) published the results of its investigation into the collapse. It found nothing substandard in the towers' design, noting that the severity of the attacks was beyond anything experienced by buildings in the past. The NIST determined the fires to be the main cause of the collapses, finding that sagging floors pulled inward on the perimeter columns, causing them to bow and then buckle. Once the upper section of the building began to move downward, a total progressive collapse was unavoidable.

The cleanup of the World Trade Center site involved round-the-clock operations and cost hundreds of millions of dollars. Some of the surrounding structures that had not been hit by the planes still sustained significant damage, requiring them to be torn down. Demolition of the surrounding damaged buildings continued even as new construction proceeded on the Twin Towers' replacement, the new One World Trade Center, which opened in 2014.[19]


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  1. ^ a b National Institute of Standards and Technology (2005). Final Reports from the NIST World Trade Center Disaster Investigation (PDF). p. 84.
  2. ^ a b The 9/11 Commission Report (PDF). 2004. p. 305.
  3. ^ "A Day of Remembrance". U.S. Embassy in Georgia. September 11, 2022. Retrieved October 27, 2022.
  4. ^ Stempel, Jonathan (July 29, 2019). "Accused 9/11 mastermind open to role in victims' lawsuit if not executed". Reuters. Retrieved October 27, 2022.
  5. ^ The 9/11 Commission Report (PDF). 2004. p. 24.
  6. ^ National Institute of Standards and Technology (2005). "Final report on the collapse of the World Trade Center" (PDF). NIST: 69.
  7. ^ National Institute of Standards and Technology (2005). Final report on the collapse of the World Trade Center (PDF).
  8. ^ The 9/11 Commission Report (PDF). 2004.
  9. ^ National Institute of Standards and Technology (2005). "Final report on the collapse of the World Trade Center" (PDF). NIST: 69.
  10. ^ a b 9/11 Commission 2004a, pp. 7–8.
  11. ^ Staff Report of the 9/11 Commission on Terrorist Attacks upon the United States (PDF) (Report). National Commission on Terrorist Attacks Upon the United States. September 2005 [August 26, 2004]. p. 24. Archived (PDF) from the original on July 12, 2014. Retrieved August 15, 2021.
  12. ^ Building and Fire Research Laboratory (September 2005). Visual Evidence, Damage Estimates, and Timeline Analysis (PDF). National Institute of Standards and Technology (Report). United States Department of Commerce. p. 27. Archived (PDF) from the original on September 11, 2021. Retrieved August 24, 2021.
  13. ^ "Timeline for United Airlines Flight 175". NPR. June 17, 2004. Archived from the original on August 24, 2021. Retrieved August 24, 2021.
  14. ^ National Institute of Standards and Technology (2005). Final Reports from the NIST World Trade Center Disaster Investigation (PDF). p. 80.
  15. ^ The 9/11 Commission Report (PDF). 2004. p. 305.
  16. ^ Staff Report of the 9/11 Commission on Terrorist Attacks upon the United States (PDF) (Report). National Commission on Terrorist Attacks Upon the United States. September 2005 [August 26, 2004]. p. 24. Archived (PDF) from the original on July 12, 2014. Retrieved August 15, 2021.
  17. ^ Evans, Heidi (September 8, 2013). "1,140 WTC 9/11 responders have cancer – and doctors say that number will grow". New York Daily News. Archived from the original on September 11, 2013. Retrieved March 31, 2023.
  18. ^ "1095 soldiers still missing since the Speicher massacre by ISIS". CNN Arabic (in Arabic). September 18, 2014. Archived from the original on September 20, 2014. Retrieved May 15, 2023.
  19. ^ "One World Trade Center officially opens in New York City, on the site of the Twin Towers". History.com. A&E Television Networks. July 24, 2019. Archived from the original on September 16, 2020. Retrieved September 16, 2020.