NEW YORK — Former President Donald Trump cemented his image as the biggest showman in U.S. politics by bringing his Make America Great Again road show to the world’s most iconic arena.

Taking a detour from crucial battleground states, Mr. Trump, joined by a star-studded cast of surrogates, told the thousands who flocked to see him at New York’s Madison Square Garden that the election is a stark choice between the status quo’s “gross incompetence” and the dawn of the “four greatest years in the history of our country.”

“I’m thrilled to be back in the city I love,” Mr. Trump said. “I’d like to begin by asking a very simple question: Are you better off now than you were four years ago?”

That “closing” question became iconic in American politics decades ago when Ronald Reagan, whom Democrats were deriding as an unstable extremist, asked it during his 1980 debate with President Carter.

“I am here today with a message of hope for all Americans,” Mr. Trump said Sunday, striking a further Reaganesque note. “With your vote in this election. I will end inflation. I will stop the invasion of criminals coming into our country, and I will bring back the American dream.”

The massive event played out as Mr. Trump and Vice President Kamala Harris prepared to focus on the final week of campaigning across crucial swing states.

Polls show the race is tight. The Trump campaign has made it clear that it feels the momentum is on its side, as evidenced by its willingness to take a detour to New York, which is not one of those swing states.

Mr. Trump said the nation’s biggest problems were caused by the lenient approach that President Biden and Ms. Harris have taken to the southern border.

“Over the past four years, Kamala Harris has orchestrated the most egregious betrayal that any leader in American history has ever inflicted upon our people,” he said.

“She has violated her oath, eradicated our sovereign border and unleashed an army of migrant gangs who are waging a campaign of violence and terror against our citizens,” the Republican said.

He announced he supports tax breaks for people caring for ailing family members.

“If I win, we will quickly build the greatest economy in the history of the world,” Mr. Trump said.

“I will protect our workers, I will protect our jobs, I will protect our borders,” he said. “I will protect our great families and I will protect the birthright of our children to live in the richest and most powerful nation on the face of the Earth.”

Meanwhile, Ms. Harris was in full get-out-the-vote mode in Philadelphia.

“So, Philly, I’ve got a question for you: Are you ready to do this?” Ms. Harris said at a stop.

“For the next nine days, no one can sit on the sidelines,” Ms. Harris said. “There is too much on the line, and we must not wake up the day after the election and have any regrets about what we could have done in these next nine days.”

In New York, Democrats projected “Trump praised Hitler” on the outside of the Garden and Trump critics likened the event to a 1939 American Nazi rally at the arena.

They also took umbrage after comedian Tony Hinchcliff referred to Puerto Rico as a “floating island of garbage.”

The Madison Square Garden rally also featured Mr. Trump’s wife, Melania, sons Eric and Donald Jr., and daughter-in-law Lara Trump, who serves as co-chair of the Republican National Committee.

In a rare political appearance, Mrs. Trump said her husband offers a vision that “builds on American greatness” and would steer the nation toward the “future we deserve.”

“For generations, this town has produced America’s most fearless leaders whose mark changed the course of the world,” the former first lady said. “New York City and America need their magic back.”

The speakers included Republican vice-presidential nominee J.D. Vance, billionaire Elon Musk, Ultimate Fighting Championship CEO Dana White, TV news host Tucker Carlson, former professional wrestler Hulk Hogan, and television personality “Dr. Phil” McGraw.

Former New York City Mayor Rudolph W. Giuliani, former Democratic presidential primary candidate Robert F. Kennedy Jr., and former Democratic Rep. Tulsi Gabbard, who recently switched her party registration to Republican, also addressed the rally.

“He is the most resilient and hardest-working human being I have met,” Mr. White said.

Mr. White noted Ms. Harris was running on “vague promises” and tried to hijack Barack Obama’s “Hope and Change” mantra.

“She can use the old Obama playbook, but she is no Obama, and she is not an agent of change,” Mr. White said, noting that the problems the nation faces and that Ms. Harris has said she can fix have been festering on her watch.

“She is the sitting vice president of the United States,” the fight promoter said.

The speakers cast Mr. Trump as a big-hearted warrior for the working class and a unifying figure. They said he has continued to fight the political establishment, refusing to surrender in the face of lawsuits and assassination attempts.

They said he would strengthen the nation by lowering the costs of groceries and energy, cutting taxes, avoiding foreign entanglements, sealing the U.S.-Mexico border, and defending free speech.

“I want to end the wars. I want to end the surveillance and censorship,” said Mr. Kennedy, the nephew of former President John F. Kennedy and son of former Attorney General Robert F. Kennedy. “I want to protect the Constitution, I want to protect freedom of speech, I want to end the weaponization of government against American politicians, and I want to end the chronic disease epidemic.”

Mr. Carlson said Mr. Trump had “liberated” the nation.

“The liberation he has brought to us is the liberation from the obligation to tell lies,” Mr. Carlson said. “Donald Trump has made it possible for the rest of us to tell the truth about the world around us.”

“He has given the rest of us the right to call B.S. on the charade,” the former Fox News host said of the nation’s political discourse, which he said the ruling class has distorted to serve its ends.

“No, you are not better than us. No, you are not smarter than us. No, you do not deserve what you have; you probably stole it. And no, you are not going to bully me into silence anymore,” Mr. Carlson said, “addressing” the nation’s coastal elites.

Various speakers described Ms. Harris as “demented,” “radical,” “the anti-Christ,” and having a “low IQ.”

Mr. Trump lost New York by more than 20 points in 2020 and 2016. The last Republican presidential candidate to win the state was Reagan, in his 49-state landslide on 1984 over Democrat Walter Mondale.

Still, the massive event in New York City was a natural fit for Mr. Trump.

For decades, he lived a little over a mile away in Trump Tower and cut his teeth as a real estate developer before he moved permanently to his Mar-a-Lago estate in Palm Beach, Florida.

The city has turned on him.

A Manhattan jury this year convicted him of 34 felony counts of business fraud, which became one of Ms. Harris’ top arguments against a second Trump presidency.

Yet Mr. Trump’s star power with many of the region’s voters is undeniable.

Excited Trump supporters from all over the New York Tri-state area wore the famous red MAGA caps and packed the Garden.

Many were wearing T-shirts emblazoned with images of Mr. Trump pumping his fist following the first assassination attempt against him with the words “fight, fight, fight” or “you missed.”

Others wore T-shirts saying, “I’m voting for the felon,” referring to the guilty verdicts, which Mr. Trump and most Republicans have derided as a political witch hunt.

Trump supporters say the rally will help downballot races in New York and give Mr. Trump a shot at flipping the state despite the long-shot odds against that.

“I’m an independent. I love the common sense part of Donald Trump’s policies and I’m here to support him and vote for him and see how we can turn this country around,” said Anthony Smith of Woodbridge.

The 47-year-old said there is a chance Mr. Trump could pull off a stunning upset in New York.

“Polls indicate that, but after talking to people that I know, a lot of people, it seems like the pendulum is coming back to common sense rather than extreme stuff,” Mr. Smith said.

Marianne, a retail worker, said people are “fed up with the way the state’s being run.”

“People are allowed to steal, like, $1,000, and it’s OK,” the 67-year-old said. “Well, it’s not OK, but they do it. So we need change.”

• Seth McLaughlin reported from Delaware.