Tunnel to Towers is keeping up the tradition of remembering and honoring America's heroes who did so much for this nation on 9/11.

The foundation kicked off its 21st annual 5K Run and Walk in New York City on Sunday, Sept. 25, 2022, to honor our nation’s fallen first responders for their great sacrifice and dedication.

This year’s event, founded in honor of all of the lives lost on Sept. 11, 2001, also spotlighted the 13 military men and women who were killed during America's withdrawal from Afghanistan in August 2021.

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Tunnel to Towers chairman and CEO Frank Siller originally modeled the run after the route his fallen brother, firefighter Stephen Siller, took through the Brooklyn-Battery Tunnel to Ground Zero on the morning of 9/11.

Now, tens of thousands of participants show up every year to join in the remembrance of Stephen Siller and other brave first responders who lost their lives in service to others.

In an interview with Fox News Digital, Siller noted the event’s "incredible" growth over the past 21 years ever since it began in 2002 with nearly 1,000 runners.

This year, the event welcomed at least 35,000 people — and closed out with a performance by country music star Dierks Bentley.

Siller believes the event has become so popular because of the unique route of the run — and the thousands of families who continue to memorialize their own loved ones.

"It is so patriotic," he said. 

"I don't think anything is more beautiful," he added. 

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Despite the passage of years, Siller said the nation continues to recall the heroism of first responders on 9/11 — while events like the one on Sunday continue to honor the sacrifices of so many Americans. 

"The Tunnel to Towers Foundation will not rest," he said. "We only get bigger and bigger every year."

"We have thousands more people [who] joined us this year than on the 20th year, which gives me great encouragement and great enthusiasm — and it inspires me and everyone involved with us to work even harder."

Participants who celebrated in Lower Manhattan post-run shared with Fox News Digital their similar feelings of pride and unity. 

"It’s just a day when it doesn’t really matter what you are," Hofstra University lacrosse player Teigue Norman said post-race. 

"We all just come together for a better cause."

hofstra university lacrosse

Hofstra University lacrosse player Teigue Norman (far left) and teammates visit the 9/11 memorial pools after completing the Tunnel to Towers annual 5K in New York City on Sunday, Sept. 25, 2022. (Fox News Digital/Angelica Stabile)

Fourteen-year-old Jordan Pieszchata of New Jersey reflected on how 9/11 first responders "never stopped" when they were called into action — a message she wanted to share with other runners on Sunday.

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"Don’t stop," she said after completing the run. 

"Never give up. They didn’t give up — nor should you."

Running trio Brian Spahn of Chicago, Logan Welge of St. Louis and Matt Muliadi of Indonesia teamed up to take on the run with plenty of pride.

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"This is really special, and a great event to remember the people involved," Welge said. 

"[First responders] are cheering you on the whole time, but they’re the ones we should be cheering for," he added. 

5k runners american flags

Tunnel to Towers 5K participants Logan Welge and Brian Spahn showed off their American flag capes post-run on Sunday, Sept. 25, 2022. (Angelica Stabile/Fox News Digital)

"We’re just a couple of Midwest kids here to support New York," Spahn said.

"We’ve got to keep this country strong and stay together — one nation under God."

Seton Hall University athletes John Luders and Abby Wingo, who ran on Team Shamrock, agreed that witnessing the participation of other firefighters while honoring those who have fallen is "really moving."

"It makes you want to sprint the whole thing," Wingo said. "It’s just so much bigger than anybody."

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Firefighters paused to reflect at the FDNY memorial wall in Lower Manhattan following the Tunnel to Towers annual 5K on Sunday, Sept. 25, 2022. (Angelica Stabile/Fox News Digital)

"No matter what you believe in, where you’re from, we all come together and do this."

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Two London Fire Brigade firefighters, Ben and Kyle, traveled all the way from the U.K. to run in the race on Sunday, along with 25 others from Paddington Fire Station, they said. 

"It feels like a great, big family," Kyle said. "It’s a really great atmosphere."

london fire brigade

Members of the London Fire Brigade showed their support for the FDNY at the Tunnel to Towers annual 5K in New York City on Sunday, Sept. 25, 2022. (Angelica Stabile/Fox News Digital)

"Americans know how to organize a run," Ben said. "We’ve got to keep coming every year and raise awareness for what the amazing firefighters in New York do."

New York City fire riders Greg Fagan, Sal Banchitta and club president Jim Finnell — who are responsible for escorting runners through the tunnel every year during the run — said it’s a job they’ll never quit.

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"We never stop serving," Fagan said. "We said we’d never forget — and we didn’t forget."

new york city fire riders

New York City fire riders (left to right) Greg Fagan, club president Jim Finnell and Sal Banchitta attended the Tunnel to Towers 5K post-run party in Manhattan after escorting runners through the Brooklyn-Battery Tunnel on Sunday, Sept. 25, 2022. (Angelica Stabile/Fox News Digital)

"Never forget," Finnell repeated. "We all had friends we lost … so we give back."

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Retired U.S. Navy service warfare officer Jim Leahy, who said he attends the Tunnel to Towers event every year, shared his own patriotism.

military and firefighter nyc

Two military servicemen and a firefighter take in the 9/11 memorial pools in Manhattan on Sept. 25, 2022. (Angelica Stabile/Fox News Digital)

"We’re big supporters of the event and the country," he said. "God bless America."

Army veteran Earl Granville, who lost his leg serving in Afghanistan in 2008, took on the run while carrying along an American flag.

veteran holds flag nyc

Army veteran Earl Granville (second from left) carried an American flag in front of the 9/11 memorial pools after completing the Tunnel to Towers annual 5K in New York City on Sunday Sept. 25, 2022. (Angelica Stabile/Fox News Digital)

Granville commented that events like the Tunnel to Towers 5K remind Americans that the first casualties of the War on Terror were 9/11 first responders.

"This is what America’s about," he said. 

"We’re coming together through a tragedy, but we should always be together."

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"Seeing us all come together in this moment — let’s keep that going," he said. "We don’t need a tragedy to come together."