Trump, a New York celebrity for decades, hoped to use the event at the iconic venue known for Knicks basketball games and Billy Joel concerts to deliver his closing argument against Democratic candidate Kamala Harris, even though the state last backed a Republican presidential candidate in 1984.
"I'd like to begin by asking a very simple question. Are you better off now than you were four years ago?" Trump said at the start of his speech on Sunday. The crowd shouted: "No."
Trump's campaign said the event at the 19,500-seat iconic arena was sold out. (AP PHOTO)
He went on to promise that he would stop an "invasion of criminals coming into our country" if he wins the November 5 election, and called Harris a "very low IQ individual".
The list of at least 20 opening speakers varied widely from former pro wrestler Hulk Hogan to former New York mayor Rudy Giuliani to Trump's sons Eric and Don Jr.
Some of Trump's introductory speakers used racist and misogynistic language in warming up the capacity crowd.
Rudy Giuliani, the one-time New York City mayor and a former personal lawyer to Trump, falsely claimed that Harris was "on the side of the terrorists" in the Israeli-Palestinian conflict and wanted to bring Palestinians to the US.
Comedian Tony Hinchcliffe used crass language in joking that Latinos "love making babies" and called the Caribbean US territory of Puerto Rico a "floating island of garbage".
Puerto Rican singer Ricky Martin posted a clip of the comments on his Instagram and wrote, in Spanish, "This is what they think of us."
Harris earlier on Sunday visited a Puerto Rican restaurant in Philadelphia in the must-win state of Pennsylvania to encourage people to vote. She posted a video on social media promising to "invest in Puerto Rico's future" as president.
Harris's campaign said the Madison Square Garden rally was "mirroring the same dangerously divisive and demeaning message" as Trump.
The Harris campaign said the rally sent the same dangerously divisive message as Trump (AP PHOTO)
Trump's 2016 presidential opponent, Democrat Hillary Clinton, has accused him of "re-enacting" a pro-Nazi rally that was held at Madison Square Garden in 1939 on the eve of World War Two.
Trump's critics have long accused him of empowering white supremacists with dehumanising and racist rhetoric.
Trump rejected the comparison to the 1930s.
"This is called Make America Great Again, that's all this is," he said on Friday.
"Today this is Donald Trump's house," said the wrestler Hulk Hogan in a speech at the New York event, later rejecting accusations that Trump is a fascist: "I don't see any Nazis in here."
US billionaire Elon Musk, who is supporting Trump's re-election bid with his X social media platform, enormous wealth and cash giveaways that have raised legal questions, was greeted to the stage with chants of "Elon".
Elon Musk has been promised a senior role in a Trump administration. (AP PHOTO)
"This is the kind of positive energy that America is all about," Musk said.
Musk, who Trump has said he would tap to lead a new government efficiency commission, said the federal budget could be reduced by "at least" $US2 trillion ($A3) trillion. Federal outlays topped $US6.75 trillion ($A10 trillion) in fiscal 2024, which ended September 30.
Trump got cheers inside the arena for his tough-on-migrants rhetoric. He vowed to ban sanctuary cities and invoke the 1798 Alien Enemies Act law to deport immigrants with criminal records.
Trump announced a new policy to provide a tax credit for family caregivers "who take care of a parent or a loved one".
Polls show the rival candidates are neck and neck in the battleground states that will decide the next president with just over a week until Election Day. More than 38 million votes have already been cast.
Trump has been seeking to tie Harris to the Biden administration's handling of immigration and the economy. Last week, Trump debuted a new attack line: "She broke it, and I promise you I will fix it."
The US economy has outperformed the rest of the developed world since the COVID crisis, and stock markets hit record highs this year.
But high prices of food, utilities and housing have roiled voters, who believe the economy is headed in the wrong direction.
Harris, who held a rally with Bruce Springsteen in Atlanta on Thursday and Beyonce in Houston on Friday, will hold another high-profile event with a speech on Tuesday on the National Mall in Washington, where she will highlight contrasts between herself and Trump.
"He is full of grievance. He is full of dark language that is about retribution and revenge," Harris said of Trump in Philadelphia on Sunday.
Trump's campaign said the event at the 19,500-seat arena, which can cost upwards of $US1 million to rent, was sold out. Tickets are free and on a first-come-first-served basis, as was the case with Harris' Houston rally.
