That same resilience played out in two other communities that endured attacks that day: Shanksville, Pennsylvania-where United Flight 93 went down after the heroic actions of its passengers and crew-and Arlington, Virginia, home of the Pentagon.
Trump said Tuesday his administration is "facing down the menace of radical Islamic terrorism", using a controversial phrase that he's insisted is necessary to accurately define the enemy.
The immediate deaths included 246 on the four planes, 2,606 in New York City and 125 at the Pentagon.
Other 9/11 ceremonies happened throughout the day as Americans marked the 17th anniversary of the terror attacks. But each year at ground zero, victims' relatives infuse the ceremony with personal messages of remembrance, inspiration and concern.
Without fail, the president's words were immediately compared to those of his predecessor, Barack Obama, who was objectively more eloquent with his 280 characters on the social media platform.
"A story of tragedy, and most importantly a story of our shared values of America as self sacrifice, duty and honor", Zinke said. "They did not sit back and let events unfold before them". But there have always been some efforts to separate the solemn anniversary from political campaigns.
"It is not a day to give speeches, it is not a day to talk about politics".More news: White House Probe Into 'Anonymous' NYT Columnist Narrows To A 'Few People'
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The president and his wife Melania sat solemnly as the names of all 40 passengers and crew members killed were read out close to where the Boeing 757 slammed into the ground in Shanksville, Pa.
"Even though I never met you", Isabella Del Corral said of her slain grandfather, Joseph Piskadlo, "I'll never forget you".
"For me, the Tower of Voices is a symbol of defiance - 93 feet tall, standing at the entrance to this memorial, defiantly speaking for our loved ones", Felt said.
"This is not a day to talk politics, it is a matter of heart: we need to be united, this is the only way to manage the pain", said Alice Greenwald, president of the memorial, on a local television station NY 1. That number includes the hundreds of first responders who were killed trying to rescue those who were in the World Trade Center when the towers were struck and collapsed.
The 40 passengers and crew members on board attempted to regain control of the jet after speaking to relatives on the phone and learning the hijacking was part of a larger plot targeting the World Trade Center in NY.
And there building continues.