Thick soot blanketed everything Bobby Valentine’s eyes could canvas when he visited ground zero in the early morning hours two days after Sept. 11.

“It was like walking through a nightmare,” Valentine recalled.

Shea Stadium in Queens, then the home of the Mets, had been transformed into a staging area. Valentine, then the Mets’ manager, assisted there. On Sept. 21, 2001, the Mets hosted the Atlanta Braves in their first game in New York since the attacks. Mike Piazza smacked a home run in the eighth inning that lifted the Mets to a 3-2 victory, providing a level of catharsis for many in a reeling city and country.

“It was a spontaneous moment of people coming together,” Valentine, 71, said. “Can that happen again in a nation that is so divisive now that it feels that we’re at war within our boundaries?”

Twenty years after Sept. 11, the United States is at another moment of crisis, but the ties between sports and patriotism have severed for some, and tightened for others. The jingoism at sporting events that temporarily surged during the Gulf War and roared back after Sept. 11 now often drives wedges, after the largest social protests in history against systemic racism during a politicized pandemic.

The playing of the national anthem and “God Bless America,” massive American flags, military flyovers and patriotic ceremonies are as ubiquitous at sporting events today as first downs, home runs and slam dunks. But the end of the war in Afghanistan, against a backdrop of social change and reflection on the dynamic between this country and its people, stokes debate on how or even whether such displays should continue.

“I don’t think that there’s anything wrong with patriotism in sport,” said Ibtihaj Muhammad, the first Muslim American to win an Olympic medal, at the 2016 Olympic Games. She added: “Sport bridges so many different people and in cultures and identities.”

But, Muhammad said, it may be time to change how the patriotism is displayed a generation after Sept. 11. When she sees a military flyover she wonders how it affects the climate or whether the money can be better used in underserved communities.

“And that’s a better way to celebrate our patriotism and our commitment to this idea of our nationality,” Muhammad said. “Why not try to elevate those who don’t have?”

Steve Kerr, coach of the N.B.A.’s Golden State Warriors, said friendly ribbing between fans, like he saw at a recent baseball game between the Los Angeles Dodgers and the San Diego Padres, is a “very indirect” show of patriotism because of the spirit and energy.

“But I also think that during the last two decades, we have all been subject to patriotic manipulation in many ways,” said Kerr, whose father, Malcolm, was the president of the American University of Beirut when he was shot and killed in Lebanon in 1984. “And because it’s directly related to the military and to the wars that we have been engaged in for two decades, it’s a strange dynamic at games, and I’m always conflicted by that dynamic.”

In the 1960s, Pete Rozelle, the N.F.L. commissioner at the time, dispatched players to Vietnam for good-will tours and mandated that players stand at attention during the national anthem. In 1968, Tommie Smith and John Carlos raised their fists at the Olympics in Mexico City. Nearly three decades later, the N.B.A. suspended Mahmoud Abdul-Rauf, a guard for the Denver Nuggets, for declining to stand during the anthem. In 2015, the former Arizona Senators John McCain and Jeff Flake released a report disclosing that the Pentagon had paid the N.F.L. and other sports leagues $6.8 million to host what they described as “paid patriotism.”

“Unsuspecting audience members became the subjects of paid marketing campaigns rather than simply bearing witness to teams’ authentic, voluntary shows of support for the brave men and women who wear our nation’s uniform,” the report said.

The back-and-forth of protest and compulsory patriotism at sporting events has come to a head over the past five years. In 2016, Colin Kaepernick began kneeling during the national anthem as a member of the N.F.L.’s San Francisco 49ers, jump-starting the current wave of peaceful protests of social injustice and police brutality against Black people and other people of color.

At first, Kaepernick sat during the anthem. He decided to kneel after talking to Nate Boyer, a retired Army Green Beret who walked onto the University of Texas football team as a long snapper and signed to the Seattle Seahawks as an undrafted free agent.

In this fraught political climate, many Republican politicians, including former President Donald J. Trump, have accused Kaepernick and other athletes who kneel during the anthem of disrespecting the military, even though Boyer recommended the gesture and Kaepernick has said repeatedly that that is not his intent.

Boyer, on a recent telephone call, said he understood that some people saw it as disrespectful. “But what I don’t understand,” he said, “what really frustrates me, is why people can’t have a different perspective on that, and still respect each other.”

He continued: “Everything seems so one way or the other, all or nothing, right now. That’s just not what that flag represents to me. I don’t think it represents that to a lot of people.”

Few athletes joined Kaepernick’s initial protest.

Bruce Maxwell, a catcher for the Oakland Athletics whose father served in the military, became the first Major League Baseball player to kneel during the anthem in 2017.

“I did it because it was what was right,” Maxwell said, adding, “I was standing up for myself. I was standing up for my family. I was standing up for the people who couldn’t be heard and/or haven’t been heard.”

By the summer of 2020, when waves of athletes protested after the police killings of George Floyd and Breonna Taylor, kneeling was common in sports and almost universal in the N.B.A. and the W.N.B.A. In a whiplash reversal, athletes like the former New Orleans Saints quarterback Drew Brees, who called kneeling “disrespecting the flag,” received criticism for their support of the patriotic exhibitions.

The protests forced organizations like U.S. Soccer, FIFA and the N.F.L. to reconfigure policies that required athletes to respectfully stand during the national anthem.

But though the N.B.A. embraced kneeling in the final months of its 2019-20 season, it pushed back when the Dallas Mavericks, at the direction of the team owner, Mark Cuban, did not play the national anthem for several games at the start of the 2020-21 N.B.A. season.

“We respect and always have respected the passion people have for the anthem and our country,” Cuban said in a statement through the team at the time. “But we also loudly hear the voices of those who feel that the anthem does not represent them. We feel that their voices need to be respected and heard, because they have not been.”

The league required the team to start playing the anthem again.

“The ritual of playing the national anthem prior to sporting events reinforces our sense of belonging,” Adam Silver, the commissioner of the N.B.A., said in an interview this week. “For generations in the U.S., people have turned to sports in difficult times in search of unity and togetherness. We saw that in the days and weeks following the events of 9/11, and we’re seeing it now during this pandemic. People crave that physical coming together because it provides a sense of stability and comfort. With sports, there is a real community aspect to them that is hard to find anywhere else.”

But the anthem doesn’t resonate with everyone in the same way, said Charles K. Ross, the chair of the African American Studies Program at the University of Mississippi.

Francis Scott Key, the national anthem’s songwriter, owned enslaved people.

“When you start talking about the millions of African Americans, their history and what their families have had to probably go through to get the opportunity to sit in that seat at that professional venue and get ready to see this game being played, they’ve got a very different kind of experience than the average white American and looking at America as this kind of holistic monolithic country,” Ross said.

The vast majority of players in the N.F.L., N.B.A. and W.N.B.A. are Black.

States like Texas and Wisconsin are considering bills that would require that the national anthem be played before any sporting event held at sites financed in part by taxpayer money.

Representative Tony Kurtz, a Republican and a military veteran, is one of the assembly members who proposed the bill in Wisconsin after Cuban did not play the anthem in Dallas. In May, the bill passed the State Assembly with a bipartisan vote, 74-22.

“I was called a fascist, a Nazi, just a whole bunch of things,” Kurtz said. “I just believe in our country. We are one nation. At the end of the day, we all still got to get along. I think that’s why it resonates so much with sports and why it resonates so much after 9/11. We needed unity in this country.”

Representative Don Vruwink, a Democrat, voted in the bill’s favor. But Vruwink, a longtime high school and youth sports coach, questioned the bill’s practicality, saying that it could not be enforced and that he worried it diluted the spirit of the anthem.

“This bill wasn’t about the logistics,” Vruwink said. “It was about a culture war, in my mind. Forcing people to say, is it good or bad, or whatever, which is unfortunate.”

Though this tension plays out at arenas, and causes fiery debates from the court to the halls of Congress, several sports commissioners, like Silver, still see a role for patriotic displays at sporting events.

“Crisis brings out the best and worst in people and companies,” said Don Garber, Major League Soccer’s commissioner, adding: “I really believe that even during the most polarizing times, sports seems to cut through all of that when it needs to most, and I continue to believe that our industry will continue to do so.”

Among the major sports, Garber was the only current commissioner in that role on Sept. 11. That morning, he was about to enter the Lincoln Tunnel when he looked up and saw the first tower on fire. He spent the night in the office of his brother, Mitch, a longtime attorney for a law firm that represented police officers out of an office near ground zero.

Cathy Engelbert, a longtime corporate executive and now the commissioner of the W.N.B.A., worked across the street from the World Trade Center. In a statement she said she remembered “vividly how sports played such a vital role in bringing our country together.”

She added: “Two decades later, I still believe that sports continues to be unifying.”

Bud Selig, Major League Baseball’s commissioner at the time, described baseball as an institution with important social responsibilities. The two most important instances, Selig said, were when Jackie Robinson broke the color barrier and when baseball returned after Sept. 11.

George W. Bush, who was then president, threw out the first pitch before Game 3 of the World Series at Yankee Stadium that year. “The reaction of the crowd showed that our country was on its way back,” Selig said in a statement. “It is inherent in every level of our game that the welfare of our country comes first.”

Muhammad, who won a bronze medal with the U.S. women’s saber team at the 2016 Games, also became the first U.S. Olympian in any sport to compete while wearing a hijab. After Sept. 11, hate crimes against Muslims escalated. Muhammad said “being a visible Muslim woman comes with its difficulties.”

“I don’t think that my experience as an American and having lived through 9/11 is any different from anyone else’s, other than the Muslim community became, like, literal targets afterward,” Muhammad said. “And I remember just that change in which people saw me, in the way that I was treated even sometimes by teachers, because I was young when it happened.”

And being Black, she said, is “10 times harder in this country.”

But that, in part, fuels her willingness to show her patriotism, including in sports.

“My parents made a very intentional effort to make sure that me and my siblings understood our own history as descendants of an enslaved community,” she said. “And so I am very proud of the country that my ancestors had built for free, and I don’t allow other people to dictate that connection to patriotism. I never have.”