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"We just have to remember them we can't let history go," said Kay Langland, who came out to show support.
Current and retired firefighters and some supporters climbed 22,000 steps of Soldier Field to honor those lives lost. That's the equivalent of the 110 stories of the World Trade Center.
"The 343 brothers we lost that day, that's my push to get through this for them. They're the ones that are going to be carrying me through these stairs," said retired firefighter Mike Murr.
Murr was still in training to become a firefighter on the day the towers were attacked. He said watching the heroic efforts of others that day impacted the rest of his career.
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"It pushed me. It made me want to pursue it more made me want to, you know, Step up to the plate and, you know, do the job to be there to be the best that I can be for everyone, for the citizens," said Murr.
Others are too young to remember the day, like the ceremony's national anthem singer 17-year-old Talia Martino.
"My mom has always made it a point for me to know the importance of today, so it's really important and it feels very good to honor those who passed away from this," said Martino.
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Others remembered exactly where they were that day.
"My husband was supposed to travel that day and he chose not to and we just stayed home and watched what was going on," Langland said.
As the country remembers the lives lost 20 years ago, the nation's departure from Afghanistan also comes to mind for many.
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"It all kinda coincides with us pulling out of Afghanistan. That's why we started the war 20 years ago. I have a daughter in the army so I just think back to where this all came from," Langland added.