In his first month as president of the United States, Donald J Trump spent three weekends at his home in Palm Beach, Florida, a palatial estate known as Mar-a-Lago. Initially he called it “the Winter White House”, but last Friday he renamed it “the Southern White House”, signalling that he is likely to make trips to the 118-room waterfront mansion all year round, at taxpayer expense. Some are joking that it has become “the Weekend White House”.

In his book The Art of the Deal, Trump, a native New Yorker, called his Florida home “as close to paradise as I’m going to get”. But that’s not why he has already visited it so often as president.

Other presidents have found in Florida a quiet refuge from their political storms. Harry Truman had a “Little White House” in Key West, in the state’s southernmost reach, where the US navy catered to his every need. Richard Nixon could relax on property he owned on Key Biscayne, near Miami. It’s where he first learned of the Watergate burglary (carried out by a team hired from the Cuban exiles living in Miami, a classic Florida irony).

Mar-a-Lago is different. It’s not just a private home, as those locations were. It’s also a commercial enterprise – specifically a club.

“For Trump it is the best and the worst,” said historian James Clark, author of Presidents in Florida. “He has the most magnificent home in Palm Beach, but he has to share it with hundreds of other people.”

Before the election, Mar-a-Lago charged a membership fee of $100,000 and annual dues of $14,000. After the election, the price of membership doubled to $200,000. In addition to using the facilities – two pools, a spa, tennis and croquet courts, and of course a beach – members have access to more than 30 guest rooms, from suites to cottages, where the cost of a stay can exceed $1,000 a night. Mar-a-Lago is also a catering facility that’s available to rent for everything from bat mitzvahs to car shows. A horse show there in 2014 featured singer Bruce Springsteen’s daughter riding in competition.

The combined membership and rental fees are a major source of revenue for the new president. According to a candidate disclosure form, Trump – who stays in a private wing of the building – made $15.6m from Mar-a-Lago in 2014.

Business and pleasure ... Trump appoints HR McMaster (left) as national security adviser at Mar-a-Lago. Photograph: Susan Walsh/AP

As the New York Times noted over the weekend, the membership rolls include “dozens of real estate developers, Wall Street financiers, energy executives” and others whose business is likely to be affected by Trump’s policies. That makes Mar-a-Lago “unprecedented in American history,” the paper reported, because it’s the first presidential home “with customers paying a company owned by the president”.

The fact that Trump’s club is making money from his presidential presence has been enough to start his critics talking about ethical problems. Trump’s second visit to Mar-a-Lago sparked further controversy. Trump had brought Japanese prime minister Shinzo Abe there to play golf. Later, as they ate dinner together surrounded by other club members, they learned that North Korea had fired a ballistic missile into the ocean off Japan, a clear test of Trump’s new administration as well as Abe’s.

Suddenly the Mar-a-Lago patio turned into a makeshift situation room, with the other members looking on, listening in and snapping pictures that they posted on social media. The Republican-controlled Congress, slow to act on other accusations against Trump, has raised questions about the wisdom of discussing state secrets amid the gawking diners of Mar-a-Lago.

Trump’s visits have also led to considerable disruptions in town. City officials are now asking all contractors, landscapers and pool cleaners to leave the island before 3pm when he’s in town, and they are urging all residents to sign up for traffic alerts so they will know which roads are closed off for his motorcades. The closures have already hurt business at the pricey Worth Avenue shops.

Despite the uproar, Trump will spend as much time at Mar-a-Lago as possible throughout his tenure in the Oval Office, predicts Laurence Leamer. Leamer, a Palm Beach resident, wrote a book called Madness Under the Royal Palms that takes readers behind the gated walls of America’s most exclusive enclave of wealth and fame. “He comes down here because he needs constant applause,” Leamer says. “He’s adored within the confines of that club.”

‘The Southern White House’ ... Photograph: AP/Carolyn Kaster

It doesn’t hurt that everywhere Trump turns in the building he sees his own image or name plastered on things, including the menu, which features “Mr Trump’s Wedge Salad” and “Three Layer Trump Chocolate Cake”. There’s even a Trump meatloaf.

The dining room is the true focal point of Mar-a-Lago. “It’s basically just a big supper club, says Leamer, who has dined there more than once. “The people who are members there don’t play tennis, don’t swim, and don’t go to the beach. The whole point is to show that you’re a member of the elite.”

This is not at all what Mar-a-Lago’s original owner had in mind.

The mansion was built by cereal heiress Marjorie Merriweather Post in 1927, at a cost of $7m. Post, at one time the wealthiest woman in the US, named her Florida home for its picturesque location between the Atlantic Ocean and Lake Worth. The architect she hired to design it, Marion Sims Wyeth, also designed the Florida governor’s mansion.

When Post died in 1973, she left her estate to the US government. She wanted it used as a winter White House – a place where a president could find solitude and rest. But in 1980 the government handed it back to her daughters because its annual upkeep cost $1m.

Post’s mansion, a mix of Italian, Spanish, Dutch and Portuguese architectural styles, is far from the only ostentatious edifice built in Palm Beach. The island has long been a haven for the extremely wealthy. It got its name when a shipload of coconuts washed ashore and the early settlers planted them to see what would grow. But what put Palm Beach on the map was railroad magnate Henry Flagler’s decision to build one of his most opulent hotels there in 1896. The Breakers, as it became known, was designed to cater to the very, very rich, offering every possible amenity – including an illegal gambling hall run by a friend of Flagler’s that stayed in business for decades, with local authorities looking the other way.

Rich man’s playground ... Palm Beach. Photograph: John Parra/Getty Images

The Breakers’ guest list included the Rockefellers, the Vanderbilts, Andrew Carnegie and JP Morgan. Some were so smitten by the island that they bought homes there, including Joseph P Kennedy, father of future president John F Kennedy. More recent residents include radio pundit Rush Limbaugh, novelist James Patterson and, until his death in 2014, Manchester United and Tampa Bay Buccaneers owner Malcolm Glazer. In 2005, when media mogul Conrad Black was indicted on fraud charges, part of his $20m bond was secured via his Palm Beach mansion, which he then sold in 2011.

Palm Beach’s reputation as a rich man’s playground had become so established by the 1940s that Hollywood writer-director Preston Sturges set one of his screwball comedies there, calling it The Palm Beach Story.

Part of Palm Beach’s appeal for the millionaires and billionaires from the 1920s through to the 50s was its exclusivity. The town was harshly segregated, with no blacks, Hispanics or Jews allowed, explains Brian Crowley, longtime political editor of the daily Palm Beach Post: “I grew up here. This was a hotbed of segregation.”

The town’s ruling class has always tried to keep tight control over every aspect of life, from the design of the business awnings to the clothes allowed in public. “As late as the 80s we had a law forbidding men from jogging without a shirt,” says Crowley.

Marjorie Merriweather Post, the cereal heiress who had Mar-a-Lago built in 1927. Photograph: Alfred Eisenstaedt/The Life Picture Collection/Getty Images

In 1985, Guardian cartoonist Garry Trudeau mocked the town’s elite in his Doonesbury strips for requiring people who worked in menial service jobs to carry a town-issued identification card. One strip joked that black motorists driving slower than 35mph would be charged with loitering. “We’re just the target of some very jealous people,” the head of the chamber of commerce told reporters. “‘We know we’re different. We’re unique and we’re far above it.”

Meanwhile the propensity of so many rich old men for marrying much younger women has led to an odd sociological phenomenon in Palm Beach, says Leamer. “They die and leave their money to their wives, and the place becomes a matriarchy.”

The main focus in Palm Beach is on “the season”, meaning the winter. That’s when all the wealthy widows who live elsewhere the rest of the year flock to their Florida mansions and get caught up in a whirl of charity balls and dinners. Nearly all of them are held at The Breakers or at Mar-a-Lago, and covered extensively by the Palm Beach Daily News, nicknamed “the Shiny Sheet”.

“They go to these charity events to see and be seen, to visit with their friends and pose for pictures and get their pictures in the Shiny Sheet,” says Crowley. “Then they all go back up north at the end of the season.”

Except for travelling back and forth between their homes and the airport, the upper crust of Palm Beach see no need to leave the island, says Leamer, “except to die, because there are no cemeteries or funeral homes on the island”.

If they did leave, though, they would discover Palm Beach is about as far removed from the rest of Palm Beach County as the Earth is from the moon. The county’s voter rolls are dominated by Democrats. Palm Beach County voted overwhelmingly for Hillary Clinton for president, not its part-time resident. (The voting precinct that includes Mar-a-Lago, though, gave Trump 64% of its ballots. The GOP’s 2012 nominee, Mitt Romney, did far better, with 78%.)

Some of Florida’s poorest people live in Palm Beach County in communities at the edge of the Everglades, no more than 20 miles from the glittering mansions of Palm Beach. “There’s great wealth here and great poverty, and never the twain shall meet,” says Crowley.

The surrounding county is more like the rest of Florida than Palm Beach is. Its mix of residents includes immigrants, many from Mexico and Guatemala, as well as factory workers and elderly retirees. This is a place where you could find animal sacrifices by the Santeria religious cult at an Audubon Society nature preserve.

A long, leisurely history ... verandah of the Palm Beach Hotel. Photograph: Geo P Hall & Son/The New York Historical Society/Getty Images

It’s also where the poorly designed “butterfly ballot” baffled so many voters in 2000 that it helped alter the course of the presidential race, further cementing Florida’s image as a swing state that controls the fate of the nation. Florida voters are notoriosly fickle, going for Barack Obama twice, but in between electing and re-electing Tea Party darling Rick Scott as governor.

Palm Beach County isn’t what attracted Trump, though. He only had eyes for the Post mansion and Palm Beach.

Trump first spotted Mar-a-Lago while on a Florida vacation in 1982. He wrote later that he knew right away he had to have it. He offered $28m and was rejected. Three years later the housing market had slumped and three other sales – to the Marriott hotel chain, to friends of country singer Tammy Wynette and to a Houston land developer – had fallen through. Trump at last picked it up for a mere $8m, furnishings included.

He was determined to make money from the property. His original plan was to subdivide it and build homes, keeping the main residence for himself, but the town’s strict zoning codes prevented that. Instead, he converted the place to a private club, one that reflects his own taste and interests. He converted the Post library, full of rare first editions, into a bar adorned with his portrait in tennis whites. He added on the 20,000sq ft Donald J Trump Ballroom, which features $7m worth of gold leaf. He also added four gold-plated sinks.

The ballroom made its debut as the place where he and his third wife Melania were wed in 2005. Tony Bennett sang, and the attendees included Hillary and Bill Clinton.

Although he inherited wealth, Trump frequently came across to much of the island as the epitome of nouveau riche. “Trump represents the biggest change to hit the island over the past 30 years,” says Crowley. “He represents the new money coming in, defying conventions.”

His long-time butler told the New York Times last year that Trump never cared to shop at any of the businesses on Worth Avenue that cater to the rich. Instead, he preferred to stick to Mar-a-Lago, popping out to glad-hand visitors during dinner or at various charity events. Occasionally he would venture out to play a round or two at the Trump International Golf Club, a 10-minute drive away in West Palm Beach, but that was it.

He soon got into legal battles with the town over his oversized flag and flagpole (80ft high, nearly double what the local ordinance allowed) and over the fact that the mansion is directly under the flight path for the local airport. Now that he’s president, though, air traffic is forbidden from entering the air space above Mar-a-Lago when he is in residence, which costs the local airport thousands of dollars.

When he first got to Palm Beach, he did something with Mar-a-Lago that irritated the older elites. He opened up his club to Jewish, black and gay members. Anyone could join, as long as they had the money. Rich people who had been rejected by Wasps-only clubs flocked to Trump’s.

Now, when Trump makes a presidential visit to Mar-a-Lago, the Secret Service takes over the parking lot. Mar-a-Lago’s new-money members are directed to use the lot of the club next door that wouldn’t let them in, greatly inconveniencing it.

For Trump, says Leamer, “that’s the sweetest revenge”.

• Craig Pittman is the author of Oh, Florida!: How America’s Weirdest State Influences the Rest of the Country, published by St Martin’s Press (£18.99). To order a copy for £16.14 go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99