From David Letterman’s emotional monologue to George W. Bush’s World Series first pitch, these collective experiences helped the nation process its shock and grief.

While the United States was still reeling after the September 11 terrorist attacks, it was the country’s comedians, musicians and screen stars, along with a symbolic sports moment, that played a prominent initial role in helping America collectively process its shock and grief.

Pop culture’s response to the attacks was all the more remarkable because the entertainment world essentially ground to a halt just minutes after the Twin Towers fell. In television, “even cable channels that…didn’t have news operations were either carrying a feed of news coverage, or some of them just put up a card that says we said ‘We are temporarily suspending programming,’” says Bob Thompson of the Bleier Center for Television and Popular Culture at Syracuse University’s Newhouse School of Communications. “Sporting events stopped. Award shows were postponed. Broadway wasn’t doing shows. It was a complete shutdown of entertainment.”

But the world of late night comedy, in particular, began planning how to return on air almost immediately. “Clearly, late night TV has become the entertainment industry’s first responders, and that really comes to the fore the week after September 11,” says Thompson, noting that several late night moments from that week have become embedded into our collective memory.

From emotional late night monologues to star-studded telethons and a presidential first pitch at the World Series, here are five indelible pop culture moments that helped Americans move forward after September 11.

WATCH: Commemorating the 20th anniversary of the September 11 attacks, The HISTORY® Channel will premiere three documentary specials, starting on September 10. Watch a preview for all three specials now.

The Return of Late Night Television

At the height of his popularity, David Letterman was considered the dean of late night. That was never more apparent than on Sept 17, 2001, less than a week after the attacks, when “The Late Show With David Letterman” returned to the airwaves from the Ed Sullivan Theater in Midtown Manhattan with a somber opening monologue that touched on the emotions many viewers were probably experiencing: grief, confusion, admiration for first responders—and solidarity with ordinary New Yorkers. “It’s terribly sad here in New York City, we’ve lost 5,000 fellow New Yorkers and you can feel it, you can feel it, you can see it. It’s terribly sad,” Letterman told the audience. “If you didn’t believe it before, you can absolutely believe it now: New York City is the greatest city in the world,” he said.

As the first late night host to return to the airwaves, “Letterman comes back and sets the standard for late night with a monologue that is still considered an extraordinary nine minutes of television,” says Thompson.

READ MORE: 9/11 Lost and Found: The Items Left Behind

A Somber ‘Saturday Night Live’

Paul Simon performs on ‘Saturday Night Live,’ as members of the Fire Department of New York, New York Police Department and Port Authority Police Department stand to the side, with (center, l-r) Police Commissioner Bernard Kerik, Mayor Rudy Giuliani, Fire Commissioner Tom Von Esses on September 29, 2001.

Dana Edelson/NBCUniversal via Getty Images

“Live from New York… It’s Saturday night” might be one of the most iconic lines in television history, and it was never more so than on Sept 29, 2001, when “Saturday Night Live” opened its 29th season. Eschewing the traditional cold open—which often parodies the biggest news story of the week—the show instead had New York native (and rock legend) Paul Simon perform his 1969song “The Boxer,” at the request of SNL executive producer Lorne Michaels, who felt the song about a young man struggling to make it in New York “would capture the strength of the city and the emotion.”

Simon was introduced by then-New York City Mayor Rudolph W. Giuliani, who was flanked by the chiefs of the city’s police and fire departments and uniformed members of both departments. After the song ended, Michaels somberly (and famously) asked Giuliani if “we can be funny now?” Thompson recalls. “Giuliani says, ‘why start now?’ and everybody gets a laugh.”

While that line is the most famous, Thompson says what happened moments later is just as significant. “When Rudy Giuliani says, ‘Live from New York,’ that had never been a more emotionally charged use of that opening line before,” he said.

READ MORE: 5 Ways September 11 Changed America

A Star-Studded Celebrity Telethon

Bruce Springsteen opens the live broadcast of ‘America: A Tribute to Heroes”‘with ‘My City in Ruins’ in New York City, September 21, 2001.

KMazur/Wire Image/Getty Images

The footage of soot-covered firefighters and police officers at Ground Zero left many Americans—including several celebrities—wondering how they could help first responders. The heads of ABC, CBS, Fox and NBC also began planning “America: A Tribute To Heroes,” a celebrity telethon that would air on all the major networks simultaneously in order to raise money for the specially created United Way’s September 11 Telethon Fund just 10 days after the attacks.

After Bruce Springsteen opened the program with his song “My City of Ruins,” which the singer described as “a prayer for our fallen brothers and sisters,” actor Tom Hanks addressed the audience with a reminder that while the musicians and actors they were about to see were not police or fire personnel, they were hoping to use their talents to help in the best way they knew how. “We are not protectors of this great nation,” said Hanks. “We are merely artists, entertainers, here to raise spirits—and, we hope, a great deal of money.”

Creating the celebrity-packed program—musical acts included Mariah Carey, Celine Dion, Billy Joel, Jon Bon Jovi and Tom Petty and the Heartbreakers, while presenters included Muhammad Ali, Will Smith and Cindy Crawford—in a little over a week was a feat organizers worried they’d be unable to pull off. So many performers wanted to participate that actor George Clooney had the idea of having them answer phones to take pledges in the background throughout the event. But getting enough phone lines to support the event almost didn’t happen. In his book After: How America Confronted the September 12 Era, journalist Steven Brill described how, with just five minutes before air, only Whoopi Goldberg’s phone was receiving calls. A panicked Clooney told the rest of the actors to fake answering the phones until the situation was resolved.

“Fake it? How can I do that?” asked actor Kurt Russell. “You’re an [expletive] actor,” Clooney replied. “Figure it out.” The phones were soon fixed.

READ MORE: How 9/11 Became the Deadliest Day in History for US Firefighters

President Bush Throws Out A World Series Pitch

As President George W. Bush got ready to throw out the first pitch ahead of Game 3 of the 2001 World Series between the Arizona Diamondbacks and the New York Yankees at Yankees Stadium, superstar shortstop Derek Jeter stopped the President to ask a question: Was he planning to throw from the mound or from just in front of it? Jeter strongly suggested he throw from the mound, noting that the crowd would boo if he didn’t.

Clad in an FDNY jacket (with bulletproof gear underneath), Bush decided to follow that advice—and ended up throwing a strike to catcher Todd Greene, to cheers from the crowd. “I had never had such an adrenaline rush as when I finally made it to the mound,” Bush, who was invited by the Yankees to attend the first game of the series in New York, would later tell MLB.com. “I was saying to the crowd, ‘I’m with you, the country’s with you.’”

WATCH: The 9/11 Flag: Lost and Found

The Concert For New York City

Paul McCartney performing at The Concert For New York City to benefit the victims of the September 11 attacks, October 20, 2001.

Frank Micelotta/Image Direct/Getty Images

Rocker Paul McCartney was on the tarmac at New York’s John F. Kennedy Airport when the World Trade Center collapsed; he was quickly ushered off the plane while a flight attendant informed him of what was happening. The former Beatle, knowing his stay in New York had been extended indefinitely, began wondering how he could use his star power to assist the city as he began an impromptu stay at a hotel on nearby Long Island.

“While I was out there [on Long Island] twiddling my thumbs,” he said, “I began to think, is there something we can do?” he told the Hollywood Reporter in 2011. He began reaching out to old friends and compatriots like David Bowie, Roger Daltrey and Pete Townshend, Mick Jagger and Keith Richards, Elton John and Billy Joel to plan what would become The Concert For New York City, a fundraiser that resembled his old bandmate George Harrison’s Concert For Bangladesh, which occurred 30 years earlier.

The show took place on October 20, 2001 inside Madison Square Garden before a crowd of firefighters, police officers, their family members and survivors of those lost. While most acts picked solemn songs, one of the most memorable sets came when The Who performed—and Daltrey and Townshend led the crowd through the band’s anthems “Who Are You?” and “Won’t Get Fooled Again,” among their other hits. As the crowd roared its approval, Daltrey simply said, “We could never follow what you did,” as a thank you.

WATCH: 9/11 Documentaries on HISTORY Vault