Robin Higgins Horwitz knew she wanted to be in London for the coronation of King Charles III, even before the event was announced for May 6. An avid British history buff, her interest in the royal family sparked as a teenager watching the 1981 wedding of then Prince Charles and Diana, Princess of Wales.

“How many times does it happen in one’s lifetime that you get to see a coronation?” said Ms. Higgins Horwitz, 58, who will travel from her home in Skokie, Ill., next week for an organized tour that covers palaces, castles and towers linked to the royal family. “It’s history in the making.”

Flags and royal emblems are already adorning the streets of London as it prepares to celebrate Britain’s first coronation in 70 years with great pomp and spectacle.

The three-day affair will include a royal procession through central London, a celebrity-studded concert at Windsor Castle, and a national holiday on May 8, as well as street parties across the country.

Areas around Buckingham Palace and the central route known as the Mall are already “crammed with people,” said Patricia Yates, the chief executive of VisitBritain, the national tourism agency. “There’s a real interest,” she added.

U.S. travelers — Britain’s biggest inbound market — are expected to lead next week’s swell of arrivals. Flight bookings from the United States to Britain are about 10 percent higher in May compared to in May 2019, before the pandemic, according to VisitBritain. According to Hopper, the booking app, they are also more expensive — round-trip airfares from the United States to London over coronation weekend averaged $733 in mid-April, 21 percent higher than a year earlier.

After the coronation dates were announced, searches for Airbnb rentals in London during the coronation weekend surged, according to the company, which reported U.S. travelers among the top guests in London around the coronation dates, along with travelers from Britain, France, Australia and Germany (the company declined to share booking numbers).

By late March, hotel bookings in London on the booking platform Expedia were 60 percent higher for the coronation weekend compared to the same time last year. By mid-April, rooms were averaging about $350 per night, according to Hopper.

Lana Bennett, the chief executive of Tours International, a British company that runs special interest tours, said U.S. visitors showed high interest in their six-night coronation tour, which Ms. Higgins Horwitz is joining and was sold out by February. “It shines a light on the country, and it gives people an opportunity to come.”

But not all travelers headed to London over coronation weekend are thrilled.

Laura Aveidi, a youth fitness instructor living in Houston, was disappointed to find out that her family vacation to London, which she booked last July, coincided with the festivities. “The city is going to be packed and it’s not ideal,” Ms. Aveidi said. “It really doesn’t interest us.”

Despite booking early, two separate Airbnb hosts canceled Ms. Aveidi’s reservations in central London, leaving her scrambling. She paid almost double her budget for a third Airbnb at the last minute. Though the company reimbursed her for some of her unexpected costs, Ms. Aveidi said planning the trip was a nightmare. “One hundred percent we would have changed the dates,” she said. (On coronation day, she and her family are taking a day trip to Liverpool to watch a soccer game instead.)

Even some royal fans who attended the Platinum Jubilee are staying home, in what may be a reflection of Charles historically being less popular than his mother, Queen Elizabeth. “They just don’t have the interest this year,” said Ralph Iantosca, a Texas-based travel adviser, who only has one client visiting London that weekend. “The ones that did have the interest don’t want crowds.”

For people making a longer journey to attend the coronation, the event is not only a celebration of Charles’s coronation, but a way of connecting to their heritage.

Paul Dabrowa, a biotech company founder who lives in Melbourne, Australia, said that being in London for the coronation is a way for him to honor his own family history. Mr. Dabrowa said his family members were displaced from Poland during World War II and resettled by British law in Australia after the war.

“I have a lot of respect for the monarchy,” he said, adding that he had also attended Queen Elizabeth II’s funeral last September. He has not yet made up his mind about her son, Charles, but will be watching the royal procession on May 6 in central London. “It’s worth giving him a chance and seeing what he’s going to do,” he said.

Pranay Manocha, a London-based software engineer, will not be with the crowds cheering.

Mr. Manocha, 43, said that the fanfare is poorly timed, considering the rising cost of living in Britain, which has left many people struggling to afford their grocery bills. Additionally, his grandparents were displaced by the Partition of India and Pakistan in 1947, a legacy of colonialism: Celebrating an institution that had left lasting pain did not seem right, he said.

“It’s going to be insufferable, almost, to see everybody celebrating the very thing that still hurts,” he said, adding that he would be going hiking in Cornwall on May 6 instead. “I hope that the weather will be nice.”

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