The White House was rocking on the night of Saturday, May 31, 1975, for the Holton-Arms School senior prom. Susan Ford, the 17-year-old daughter of the 38th president of the United States, did the bump and the hustle in the East Room until one A.M., along with her classmates and their dates.

It was the only prom ever to be held at the executive mansion, which makes it an odd event in White House social history, right up there with President Andrew Jackson’s cheese party of 1835, which saw some 10,000 visitors gobbling up a wheel of cheddar that weighed nearly 1,400 pounds, and John F. Kennedy’s more exclusive skinny-dipping shindigs in the White House pool.

Susan had been a student at the Holton-Arms School, an academy for girls in Bethesda, Maryland, since her freshman year. The members of the class of ’75 paid the cost of the prom— $1,300—after raising funds at bake sales and school fairs.

Tablecloths were made out of floral pink-and-yellow sheets. The menu included those staples of 1970s cuisine, Swedish meatballs and quiche, as well as a nonalcoholic punch made of tea, lemonade, soda, grape juice, and sugar. Susan and her classmates assembled the centerpieces—candles in a setting of daisies, tulips, lilies, sweet peas, and ming fern.

“The girls wore long dresses, light makeup, casual hairdos, and, in many cases, orchid corsages,” the Associated Press reported. “Many of their escorts, in black or white tuxedos, wore boutonnieres and below-the-collar length hair.” An AP wire photo accompanying articles that ran nationwide captured Susan and her date dancing (butt) cheek to (butt) cheek, along with a caption noting that the young couple was doing “the new dance, the bump.”

“Susan, at that age, was strikingly beautiful,” says Sally Alexander, a retired English teacher at Holton-Arms, who was one of six chaperones. “And it’s a great deal of fun to watch a bunch of beautiful young girls with handsome young men, all dressed up. They were clearly excited about being where they were, but they were not uncomfortably awed. It was a beautiful affair.”

At the time of the prom, President Gerald R. Ford and the First Lady, Betty Ford, were en route from Belgium to Spain as part of a diplomatic tour of Europe. In their place was the president’s sister-in-law, Janet Ford, “a small figure in a white lace dress, casting a tolerant but observant eye on the proceedings,” as The New York Times described her.

One student who attended, Paul Shorb, a freshman at Williams College, regretted the absence of Susan’s father. “I’m a Democrat,” he told a reporter, “and I’d like to ask him some questions.”

Security was not what it is now. There were no bomb-sniffing dogs or counterterrorism agents on the grounds. Still, those who planned to attend had to provide their names, birth dates, and Social Security numbers, for Secret Service review, by April 15.

One name on the list was Gardner Britt—Susan’s longtime boyfriend—but they broke up after a disagreement over the Equal Rights Amendment, according to a story in People magazine, which was then in its infancy.

Susan had the same opinion on women’s rights as her firebrand mother and fair-minded father, a centrist Republican who had been a strong supporter of the amendment going back to his days in Congress, where he represented Michigan’s Fifth District from 1949 to 1973. The upshot was, less than a month before the event, she didn’t have anybody to go to the prom with. “I had broken up with Gardner Britt, whom I had dated for a long, long time,” she says, “and I didn’t have a date.”

Now 57, Susan Ford Bales is a grandmother living in Tulsa, Oklahoma, with her second husband, Vaden Bales, an attorney who sits on the board of the Betty Ford Center, the addiction recovery clinic that merged with the Hazelden Foundation in 2014 to become the Hazelden Betty Ford Foundation; Ford Bales was formerly its chairwoman. When she first went to Holton-Arms as a 14-year-old freshman, in the fall of 1971, her father—as House minority leader—was the highest-ranking Republican in Congress.

Like a dozen or so other girls at Holton-Arms, Susan was a boarder, and the start of her residency on campus marked her first time living away from her modest home in Alexandria, Virginia, where she had grown up with three older brothers, Michael, Steven, and Jack. In the dormitory she learned to smoke and play bridge.

Following the resignation of disgraced vice president Spiro Agnew on October 10, 1973, her father—who was born in Nebraska and raised in Grand Rapids before becoming a football star at the University of Michigan—found himself appointed to a brand-new job. Soon afterward, the Symbionese Liberation Army, which would gain notoriety for its kidnapping of the publishing heiress Patty Hearst, made a threat against Susan. And so she moved back home, to Alexandria, since Holton-Arms could not accommodate her Secret Service detail.

“The vice president’s family didn’t have Secret Service back then,” Ford Bales says. “I had Secret Service before my mother did.”

(The Ford family never resided at Number One Observatory Circle, because it was in the process of being transformed into the official residence for the vice president at the time; until 1977, the second-highest-ranking member of the Federal government lived in his private home.)

When President Richard M. Nixon resigned on August 9, 1974, following the Watergate scandal, Susan’s unassuming dad became the first man to hold the offices of vice president and president without having been elected to either. As a transition team cleared out Nixon’s stuff from the White House, cameras captured the new leader of the free world as he picked up the morning paper from the front step of his suburban home.

Susan liked life in the White House, partly because, after having been raised in a crowded house when she wasn’t living in a dorm, it was the first time she had ever had a bathroom to herself.

In the fall of the 1974-1975 school year, not long after the new president had told the country, as part of his barebones inaugural address, “Our long national nightmare is over,” one of Susan’s classmates, Gail Frawley (now Granowitz), had an idea. “We were having our prom meeting, and I said, ‘Why don’t we have the prom at the White House? Let’s ask Susan if it would be O.K.,’ ” she says.

Susan sought the approval of the White House chief usher, Rex Scouten, who was in charge of official functions, as well as the permission of her parents. “They said, ‘Yeah, as long as you pay the expenses, so it’s at no cost to the Federal government,’ ” Ford Bales recalls. “That’s what I remember.”

At Holton-Arms, Ford Bales was, in her words, “a B, C student.” She liked horseback riding, needlepoint, tennis, skiing, and photography. “In those days, you were cool, to have a camera hanging off your hip,” she says.

The only one of the four Ford children young enough to reside full time at the White House, she added freshness to Washington life in the aftermath of the dour Nixon years. The press found it amusing when she barged into the Oval Office to ask her father for her allowance, and she was photographed with Shan, her Siamese cat; and, again, in gym shorts and sunglasses, while washing her car on the White House driveway.

“Susan was very popular, and her social life was very important to her,” says Sally Alexander, who was head of the Holton-Arms English department in 1975. She adds that it was complicated for Susan, after she had made the transition from a relatively anonymous congressman’s daughter to someone in need of a security detail. “Her Secret Service men used to hang out in my office,” Alexander says. “I asked one of them one time, ‘When Susan goes on a date, how close do you have to be?’ He said, ‘Sally, our job is to protect Susan from outside danger, not to protect her from herself.’ ”

Her new status attracted unwanted attention from a fellow student on one occasion, Alexander recalls. “I remember one of our middle-school girls started writing Susan notes. It was as if Susan had ceased to be a senior at Holton and had become a princess. ‘Oh, maybe Susan will advise me about things that make me unhappy.’ The Secret Service had to get into that. Things like that were hard for Susan. She just wanted to be herself.”

But her new circumstances played to her advantage when it came to the site of the Holton-Arms prom.

In February, while the prom committee honed the details, the First Lady and the First Daughter (who was still planning to attend the affair with her longtime beau, Gardner Britt) took the shuttle to New York to visit a 31-year-old fashion designer, Albert Capraro, for a fitting at his Seventh Avenue office. After choosing clothes for an event she planned to attend in early May, the Shenandoah Apple Blossom Festival, Susan selected a “mandarin-neck slender jersey dress” for the prom, reported The New York Times.

Capraro, a former assistant to Oscar de la Renta who made his clothing in the U.S.A., was an easy choice as dressmaker for the First Daughter. “We bought lots of clothes from him,” Ford Bales says. A more difficult task was finding a band that could pass the White House security test.

“I was told that we had to choose a band that didn’t have any kind of drug charge,” recalls Helen Clark Atkeson, who chaired the prom committee and is now a lawyer in Denver. “They wanted to keep it squeaky clean, and it was pretty hard to find someone who met the criteria.”

“We tried to get the Beach Boys,” Ford Bales recalls.

The Beach Boys were interested enough to reduce their fee significantly, but negotiations broke down when the band insisted on filming the event for later use. And so the committee ended up choosing two less known bands: Sandcastle, a professional outfit from Richmond, Virginia, that played Top 40 songs at more than 200 shows a year; and a group that was more of a wild card, the Outerspace Band, whose long-haired members lived communally in a 12-bedroom, ramshackle house in Wendell, Massachusetts.

Formed in 1968 at Trinity College in Hartford, Connecticut, the Outerspace Band was a six-piece ensemble with a repertoire heavy on original songs and stylistic similarities to the Band and the Grateful Dead. Somehow these scruffy fellows—one of whom had a sister who was friends with a Holton-Arms student—passed Secret Service muster.

Eric Weiss, a Trinity alumnus who managed the band, worked out the details with the prom committee and the White House, agreeing to a fee of $350. “I think the contracts were signed in the White House,” says Weiss, now a lawyer in Manhattan. “The point of that show was to be the first band that had ever played at a prom there. Why not do a show at the White House, from the point of view of the band’s career?”

But in a time when the lines between the establishment and the counterculture were brighter, its members worried that the gig might be perceived as a kind of sellout.

“Playing at the White House will be a mild tongue-in-cheek thing for us,” the bass player, John “Klondike” Koehler, told the Baltimore Evening Accent about a month before the show, “but we all think it’s fantastic that the First Family is loose enough to permit a rock group to play for the first White House prom.”

On May 2, with 29 days to go before the prom, Susan was crowned the queen of the 48th Shenandoah Apple Blossom Festival, in Winchester, Virginia. Her father placed the crown on her head. The apple trees were in bloom; Bob Hope served as Grand Marshal; and Susan enjoyed having a chance to be in the company of her dad away from the tumult of Washington. “It’s a very special time between a father and a daughter,” she says.

As part of her duties, she attended various functions in the company of three young men who took turns escorting her. One of them was William Pifer, a 21-year-old premed student at Washington and Lee University. They hit it off. “I invited Billy to be my date after that,” says Susan. He said yes.

On May 31, Pifer made the drive from Winchester to Washington. “You’re driving up to the White House, and everybody’s expecting you, and you’re the only one in the car,” he recalls. “That’s pretty over the top.”

He and Susan went by limousine to the Potomac River, where the Sequoia, a 104-foot, wooden-hulled yacht operated by the Navy and used by the executive branch for social functions, was docked. Franklin Delano Roosevelt and Winston Churchill had discussed war strategy while on board, and it was also where Kennedy had celebrated his last birthday.

The Sequoia was later sold by President Jimmy Carter in a gesture meant to signal that the presidency was not some imperial office. “Why they ever sold that thing, I don’t know,” Ford Bales says. “There was an old elegance about it.”

Along with four other couples who were going to the prom, Susan and Billy cruised the river as the sun went down. The temperature was around 80 degrees on that humid evening, and there was a light breeze. Press reports from the time say the dinner served on board was beef Stroganoff on rice, with white wine.

Back at the White House, the six chaperones, including the English teacher Sally Alexander and the Holton-Arms headmaster, James Lewis, were preparing for the teen onslaught in the company of Susan’s aunt, Janet Ford. “She received us in the family quarters, where we were offered a cocktail, which was very funny,” Alexander says. “Our headmaster was very strict: We could never drink before an affair. But it was whatever you asked you for! I had a vodka and tonic.”

The guests began to arrive at 8:30, pulling up to the diplomatic entrance, according to the Associated Press. As they got out of their cars, there on the Constitution Avenue side of White House, they could glimpse the Washington Monument. Guests showed their name cards to Secret Service personnel before stepping inside.

“Picture a 17-year-old in a prom dress driving to the White House,” says Mary “Mimi” Conger, who was the Holton-Arms honor council president during her senior year and is now a fund-raiser in Alexandria. “We got to drive in through the gate on the South Lawn driveway. We stopped in front of the portico and got out. We went through the round room and then through those double doors to a long hallway with red carpet. On the right and on the left, it was cordoned off, and I remember a throng of reporters. To me, it was like my vision of a Hollywood premiere.”

“My date drove up in a beat-up Ford,” says Cynthia Wein Lett, another member of the Holton-Arms class of 1975 who is now an international etiquette expert, career guidance counselor, and author in Silver Spring, Maryland. “It was not my first time in, because I knew Susan. I had been there a few times before, but not in a prom dress, and not with a guy in a tuxedo. The first half hour or so there was a lot of press. The first question I got was, ‘Aren’t you just thrilled to be here?’ And I remember saying to them, very cheekily, ‘I am. Aren’t you?’ ”

“I was wearing a white dress,” says Gail Frawley Granowitz, who is now an anesthesiologist in Bridgewater, New Jersey, “and I told a reporter, ‘I feel like Marilyn Monroe.’ I didn’t even know who Marilyn Monroe was! My date had, like, Harry Potter glasses, taped in the front. I think he became a sprout farmer in Vermont.”

The musicians with Sandcastle and the Outerspace Band were in two large dressing rooms in the basement, getting ready. The Outerspace contingent felt out of place in all the grandeur. They had opened for Commander Cody and B.B. King, and now they were playing a prom. A White House prom, but still, a prom. The setting only made it more absurd.

They had driven down from Massachusetts in an old Chevrolet Suburban, for the six band members, and an International Harvester truck, for the manager, two roadies, and the equipment. Their confusion over what to wear onstage suggested their discomfort. They were used to wearing whatever they felt like when they played the clubs in the Northeast, from Baltimore to Boston, and now they had to look presentable.

“We had the idea of dressing up like riverboat gamblers,” Weiss says. “Very Americana. This was 1975. So I got the name of a costumer down in Washington and had them devise some riverboat gambler outfits, which were going to consist of mourning suits and tails. When we went down there to do the final fitting, the band kind of freaked out and said, ‘You know, we look really stupid.’ And so we went and did the normal thing and rented tuxes. I had a meltdown when this happened. ‘Don’t you get it? You’re going to get your picture in the news by doing this!’ The point was, this wasn’t a gig for financial gain—it was a great opportunity to get a record contract.”

One band member, a singer, songwriter, and guitarist named Eliot Osborn, later wrote up his impressions of the event in a 1976 issue of Oui, a porn magazine that had a feature well larger than those you will find in most serious publications today, in an article headlined “Bumping with Susan at Jerry’s: The Ousterspace Band Invades the White House and Attempts to Capture the President’s Daughter with Rock Music.”

Early in the story he described the arrival of the “Chevy full of hippies” and his interaction with a Secret Service officer: “Anxious to look as unstoned-out as possible, I am leaning halfway out the window by the time he reaches us. ‘Howdy. We’re from Outerspace and we’re meant to be inside.’ ”

As the Suburban rolled down the long driveway, a band member pulled down his pants and pressed his butt cheeks “firmly to the passenger side window,” Osborn wrote. When the musicians changed clothes in the basement, they considered engaging in a popular 70s pastime—streaking—through the Oval Office, only to decide that “it would be too hard to coordinate.” Another band member considered plastering a bumper sticker he had brought along with him (it read, “Who Killed J.F.K.?”) to a painting, only to think better of it.

The seasoned pros of Sandcastle, who were accustomed to playing weddings, proms, and corporate events four to six times a week, did not share the same anxiety about the show and thus did not feel the need to engage in any such shenanigans.

In a time of “stagflation,” a catchword of the day meant to convey an economy marked by aspects of a recession and inflation, the message went out that the privileged girls of Holton-Arms (which has counted Jacqueline Bouvier, Julia Louis-Dreyfus, and Brooke Astor among its students) were not freeloading. “This party isn’t costing the taxpayers a cent,” a White House spokesman told The Times. “The senior class is paying for everything—food, flowers, music and labor.” The only sticking point was the Sequoia excursion. “Oh, God, I’m going to get the bill for it,” Susan told The Times.

She arrived at 8:45 P.M., 15 minutes after the official start time. The Outerspace Band started playing at nine sharp to a mostly empty East Room. Susan was among the first on the dance floor. As The Times described it, she was “gyrating with William Pifer, her escort, to a cacophony of sounds from a group known as the Outerspace.”

A reporter from Mademoiselle, Janice E. Kaplan (later the editor in chief of Parade), looked on with a jaundiced eye: “It was a curious scene: all these reporters gazing at perfectly ordinary students, making a hero out of the kid with pimples, a star out of the too-fat girl in the corner. And because they were being given the Frank Sinatra treatment, the students—74 high-school seniors and their dates—responded like so many Frank Sinatras.”

The party didn’t get cooking, as the musician Osborn saw it, until the Outerspace Band’s lead guitarist stepped up to a microphone and said, “Have you ever met that funny reefer man?” “It was a joyous question to pose within these walls,” Osborn wrote, “and the crowd shows signs of life. Jackets begin to drape the chairs; high heels scatter about.”

The dance floor was crowded after that. “I hardly remember anything but dancing up a storm and going outside to get cool,” says Helen Atkeson. At one point Susan danced with the Outerspace Band’s bass player, John “Klondike” Koehler, which sent Osborn into a reverie: “As she raises her arms above her head, her body presses against the fabric, and not until she lowers them with a laugh do I draw a breath. It comes as a surprise, this heat in my blood.”

(The Outerspace Band ended up getting some press attention and prize bookings for the night’s work. They played CBGB in New York and received positive notices from Variety, the New York Daily News, and The SoHo Weekly News. But in a musical atmosphere of punk and disco, the record deal they sought never materialized. Still, they never gave up: the band remains active, playing to a small following in rural Connecticut, Martha’s Vineyard, and elsewhere.)

Sandcastle took over moments after the Outerspace Band departed the East Room. The seven-piece band, with four horn players, was able to re-create the popular hits of the day, everything from the Doobie Brothers to the Ohio Players. While playing the 1968 Archie Bell & the Drells funk hit “Tighten Up,” a Sandcastle front man, Billy Etheridge, got down from the riser and danced with Susan. Was she a good dancer? “Oh yeah!” Etheridge says. “Kids in those times? Heck! Absolutely, she was.”

The party chugged on until one A.M., a half hour beyond agreed-upon stop time. Susan, her date, and a few others (including Aunt Janet) went upstairs to the family quarters, while their classmates scattered to private parties. Nobody was drunk, as Pifer recalls it: “No extreme behavior,” he says. “It may have been the setting, it may have been the group.” He spent the night in a White House bedroom, as did a few of Susan’s friends. “Not many people have done that, and I didn’t have to pay $100,000 to do it,” Pifer says.

“He was a great prom date, and we dated for a while,” Ford Bales says. “I don’t know why we went our separate ways.”

(Billy and Susan saw each other again at the 2001 Shenandoah Apple Blossom Festival, where Tyne Vance, Susan’s daughter with her first husband, a Secret Service agent named Chuck Vance, was the queen. “I made a point of catching up with her and saying hello,” Pifer says.)

After attending a post-prom party at a classmate’s house, Gail Frawley Granowitz and her date (the boy in the taped eyeglasses) drove back to Washington. “We watched the sun rise from the Lincoln Memorial,” she says.

A week after the White House prom, President Ford addressed the Holton-Arms senior class at the graduation ceremony. He was a year and a half away from being defeated by Jimmy Carter in the 1976 election, and his speech included lines in support of the Equal Rights Amendment (which has still not been ratified) that would likely not be spoken by a Republican president or presidential candidate today:

“Before America completes its bicentennial celebration, I hope the Equal Rights Amendment will be part of the United States Constitution. For E.R.A. also stands for a new era for women in America, an era of equal rights and responsibilities and rewards. The rough but rewarding task for your generation, of each of you, will be to see that recent progress in equal opportunity becomes regular practice.”