This September 11 marks 23 years since the terrorist attack on the World Trade Center and the Pentagon, an event that respondents increasingly say impacted American lives forever, a USA TODAY/Suffolk University poll found.

On the morning of Sept. 11, United Airlines Flight 175 and American Airlines Flight 11 departed from Boston en route to California before hijackers crashed them into the North and South towers of the World Trade Center in New York City. American Airlines Flight 77 hit the Pentagon, while passengers attempted to overtake United Airlines Flight 93 from hijackers before it crashed in a field in Pennsylvania.

The 9/11 attacks left 2,977 dead across New York, Washington, D.C. and Pennsylvania, according to the 9/11 Memorial and Museum. That total includes the 2,753 who died in New York, 184 people at the Pentagon and 40 people who died when Flight 93 crashed in Pennsylvania.