Hundreds of police officers are expected to be out in force and roads will be closed in Midtown Manhattan for a private, two-day event at Madison Square Garden around the anticipated wedding of Taylor Swift.

Beginning on Thursday, officers from the New York Police Department, Amtrak and the Metropolitan Transportation Authority Police Department will be deployed around the Garden to patrol the event, which is expected to be a celebration of Ms. Swift and Travis Kelce’s wedding, according to people familiar with the matter.

Both days are believed to be closed to the public. The couple has invited about 100 people to a rehearsal dinner at the Infosys Theater, a venue inside the Garden, on Thursday at around 6 p.m., according to an internal police memo with details about the gatherings.

The memo is titled “Taylor Swift wedding at Madison Square Garden.”

A spokeswoman for the Police Department said plans for the event have not been finalized.

On Friday, as many as 1,000 guests are expected to arrive at the Garden for a larger celebration, with possible stage appearances, according to the memo. The doors to the arena will open around 4 p.m. for a cocktail hour on the sixth floor, followed by “a wedding and reception in the arena” beginning at around 5:30 p.m., the memo says. The event is expected to end around 2 a.m.

Ms. Swift has also applied for permits to close nearby streets, according to the two people familiar with the plans. On Friday, those are expected to include West 31st and West 33rd Streets bordering the Garden.

A police detail is planned for the rehearsal dinner on Thursday, according to a law enforcement official familiar with the plans.

Kenneth Corey, the former chief of department at the N.Y.P.D., said that hundreds of police officers would likely be needed to keep crowds safe outside the arena, in addition to the private security team Ms. Swift has hired.

“There is nothing comparable to her level of stardom and her fan base — you’re on the level of Elvis, Michael Jackson or the Beatles in their heyday,” he said. “I was at the N.Y.P.D. for almost 35 years, and there was no wedding near this scale.”

Ms. Swift’s fans are famously enthusiastic and loyal, and hundreds or thousands of them could show up outside the arena. The heat wave hitting the city from now through Saturday could also present challenges in terms of keeping fans safe, officials said.

The police will need to set up concrete barriers similar to ones erected during the N.B.A. national championship games to keep fans safe from any terrorist threats, including ramming vehicles, Mr. Corey said.

“Because of who she is and who he is, that is a very attractive terrorist target,” he said.

The added police presence will come over the long Fourth of July weekend, at a time of already elevated spending for the city’s Police Department.

In early June, Jessica Tisch, the city’s police commissioner, told City Council members that the department expected to spend about $92 million in overtime to keep pace with the “historic demands” of ensuring public safety at the city’s summer events, including the N.B.A. championship and festivities marking America’s 250th anniversary.

It was not clear whether the cost of providing security around Ms. Swift’s wedding was included in that tally.

Some New Yorkers have complained about the city shouldering any additional costs and travel headaches associated with Ms. Swift’s event.

Asked about the preparations for the event, a spokesman for the M.T.A. said: “We expect service and access to Penn Station to remain normal throughout the holiday weekend.”

Grace Rauh, the executive director of Citizens Union, a government watchdog group, said that the festivities were positive for the city and its image and an appropriate use of resources.

“This is a really fantastic advertisement for what’s so great about New York,” Ms. Rauh said. “We get it. We’re from here. She could get married anywhere.”

Scott Munro, the president of the city’s detectives union, did not agree.

“They should have their wedding in Pennsylvania or wherever she’s from,” he said, citing high levels of exhaustion among officers who have already worked extraordinary amounts of overtime.

In the past month, about 5,000 detectives have logged 85 hours of overtime because of the N.B.A. finals and the World Cup, Detective Munro said.

“Can we take anything else on here?” he said. “I think Travis Kelce and Taylor Swift should be thanking every officer standing out there in the heat, away from their families and working.”

The Police Department will be “stretched pretty thin that weekend” because of the other scheduled events celebrating the nation’s 250th birthday, Mr. Corey said.

“The demands on the department, in terms of planned events, is probably unmatched in history,” he said.

Ms. Swift has prioritized privacy and safety over the years, and she has also faced threats in the past. In August 2024, she was forced to cancel three shows in Vienna after the authorities learned of a plot to attack one of her concerts. The authorities raided a house in Austria, where they said they found bomb-making components, machetes, knives, counterfeit money and Islamic State propaganda. A 21-year-old man was convicted of planning the attack.

Ms. Tisch had already ordered officers to work 12-hour shifts through the World Cup, which will end on July 19 at MetLife Stadium in East Rutherford, N.J.

The deployment for Ms. Swift’s event will be intense, but nothing like the massive show of force that surrounded the N.B.A. finals, when thousands of officers were sent to monitor teeming crowds of fans and a victory parade for the Knicks. The police created a “frozen zone” from West 29th Street to West 35th Street between Sixth and Eighth Avenues, blocking the street from traffic and most people.

Mr. Corey said that in a city that is constantly hosting giant parades, dignitaries and other large-scale events, a big party at the Garden should feel like another day at the office.

“Is there ever a good time in New York City?” he said.