Three years ago this month, Vice President Kamala Harris moved into her official residence in northwest Washington, a quiet 73-acre enclave where the U.S. Navy keeps an observatory as well as the nation’s master clock. Early in her stay she saw evidence of digging near her house, and after asking around, learned that an archaeological team had recently found part of a foundation of an Italianate villa, known as North View, that had been there more than a century and a half before.

Near the villa, the team had found something else: A brick foundation of a smokehouse used to cure meat. Ms. Harris did not have to be told who had used it. Well before moving to the new residence, the nation’s first Black vice president had been told by aides about the 34 individuals who once lived on the property against their will. A subsequent opinion essay for CQ Roll Call was the first mention of it in the news media.

The names of the enslaved people were recorded in a document of the era. Peter, Mary and Ellen Jenkins. Chapman, Sarah, Henry, Joseph, Louisa, Daniel and Eliza Toyer. Towley, Jane, Resin, Samuel, Judah and Andrew Yates. Kitty, William, Gilbert and Phillip Silas. Susan, Dennis, Ann Maria and William Carroll. Becky, Milly, Margaret and Mortimer Briscoe. Richard Williams. Mary Young. John Thomas. Mary Brown. John Chapman. William Cyrus.

They ranged in age from four months to 65 years, and in skill from winemaking to carpentry. Five of them would go off to the Civil War as Union soldiers. Another would flee at age 13, destination unknown. For those who remained on a property that was known at the time as Pretty Prospects, the abject conditions of their lives are hinted at in documents now preserved at the National Archives.

Mortimer Briscoe, 30, “had one of his toes frost bitten, but is otherwise sound.” John Thomas, 41, “has three fingers on his left hand injured by a corn sheller” but “can drive the carriage and work as well as before.”

Until these enslaved people and roughly 3,000 others in the nation’s capital were emancipated by an act of Congress on April 16, 1862, the 34 inhabitants of Pretty Prospects were the property of a widow, Margaret C. Barber, who lived in the North View villa. Together they constitute a largely unknown chapter in a historic property whose famous resident today believes herself to be descended from an enslaved Jamaican.

After learning about the smokehouse, aides said Ms. Harris asked if any other evidence about the 34 enslaved people had been uncovered. No, she was told. But the discovery, which has now been documented in a new report that will soon be published by the District of Columbia Historic Preservation Office, prompted Ms. Harris to do some digging of her own.

Aides said she studied the old map that the archaeological team had consulted, dated 1882, which displayed the exact location of North View and the nearby smokehouse. About a quarter of a mile from where she lives now was a long-gone dwelling referred to as “Negro House,” where the 34 enslaved workers lived.

Ms. Harris then began poring over photographs taken on the property during the past half-century. The subjects were vice presidents, all white males, with their families and guests. The images conveyed nothing about the role Black people played in the history of the nation’s capital, much less on the property itself.

A Widow on a Farm

The history of a slave farm that then became the U.S. Naval Observatory and today the residence of the nation’s first Black vice president has previously been told only in fragments. This account is based on interviews with associates of Ms. Harris. It is also based on information provided by the Naval archaeologist who unearthed the smokehouse, Brian Cleven, and on a trove of historical literature, much of it culled from archives and libraries by the Washington historian Carlton Fletcher.

Ms. Harris has never mentioned the residence’s legacy of slavery in public remarks. Aides said the very idea of moving to such a place only became palatable to her once she was assured that her new home was not the same structure where Ms. Barber’s servants once worked, and that they had been emancipated three decades before it was built.

The Obamas could relate. Michelle Obama, in her speech to the 2016 Democratic National Convention, cited the fact that she lived in the White House as a Black first lady as “the story of generations of people who felt the lash of bondage, the shame of servitude, the sting of segregation, but who kept on striving and hoping and doing what needed to be done so that today I wake up every morning in a house that was built by slaves and I watch my daughters — two beautiful, intelligent, Black young women — playing with their dogs on the White House lawn.”

C.R. Gibbs, a local historian, said that many tourists are unaware of this chapter in Washington’s history. “What people don’t realize when they come to visit the Smithsonian Museum, the Washington Monument, the Capitol or the White House is that they’re standing on slave-worked land,” he said. “And the same holds true with the vice president’s residence.”

North View was built in the early 1850s for a wealthy Baltimore planter, Cornelius Barber. His wife Margaret was the offspring of a viticulturist, John Adlum, whose vineyard on the banks of Rock Creek drew admirers like Thomas Jefferson and John Adams. Five of the Barbers’ six children perished from disease, as would the father in 1853, leaving the 43-year-old widow to mind the country estate.

But she had help. The 34 enslaved farmhands and domestic servants under Ms. Barber made her second among the city’s slaveholders. (The first, the tobacco planter George Washington Young, owned 68 people of African descent.) Ms. Barber frequently rented out her men to neighbors who owned farms, tanneries and slaughterhouses. Throughout the 1850s, she netted an annual income of around $1,600, or about $61,000 in today’s currency.

One of Ms. Barber’s female domestic servants, Ellen Jenkins, had been bequeathed to her by her viticulturist father in his will, with the stipulation that Ms. Jenkins would be freed from servitude upon turning 50. But Ms. Barber described Ms. Jenkins in a document as a “good cook” and did not relinquish her servant until the 1862 law emancipated Ms. Jenkins, when she was 60.

Ms. Barber gave up Ms. Jenkins and her other enslaved workers only after hiring a lawyer, who argued to a government committee that the widow was entitled to compensation for her loss. She sought $750 each for them. In the end, Ms. Barber settled for $270 per worker, totaling $9,000, or about $336,500 today. She moved out of the villa, whose grand paintings and chandeliered ballrooms were later defiled by Union soldiers. Ms. Barber died of influenza at age 80 in 1892, around the same time North View was torn down.

A Return of Black History

Today Ms. Harris lives in a white turreted Queen Anne-style three-story building, one with a history more less fraught than that of the villa it replaced.

Built in 1893 for the superintendent of the naval observatory and later the home of the Chief of Naval Operations, in 1974 it was designated by Congress as the vice president’s official residence. Walter F. Mondale moved in with his family three years later, abiding with good cheer the not-yet-updated plumbing. He chortled about it in interviews, and said the family became friends with the plumber. The hot water went out a lot.

At some point during the 1980s, Vice President George H.W. Bush added a horseshoe pit to the property. His successor, Dan Quayle, had a putting green and a swimming pool installed, which later endeared Mr. Quayle to Vice President Joseph R. Biden Jr., who along with his wife Jill were fond of taking evening dips there. Vice President Dick Cheney preferred the residence’s hammock, where he oversaw the romping of his Labradors, Jackson and Dave. The Pences contributed a beehive and hosted pumpkin-decorating activities on Halloween.

A notable first came two years ago, when Ms. Harris and her husband Doug Emhoff welcomed a gathering of predominantly Black Washington families to celebrate Juneteenth. In her off-the-record remarks that day, the vice president made a passing reference to the 34 individuals who once lived on the property against their will.

Ms. Harris has sought to reconnect the residence with the Black American experience and to showcase the works of minority artists. Last September she hosted a hip-hop concert on the lawn, dancing with 400 guests to performances by Lil Wayne and Q-Tip. She turned to a Harlem-based designer, Sheila Bridge, to reimagine the interior.

In decorating its walls, Ms. Harris passed on landscape paintings offered to her by the Smithsonian and instead installed art that includes works by the Black photographers Carrie Mae Weems and Roy DeCarava, a painting by the Cherokee artist Kay Walkingstick and a quilt by the women of Gee’s Bend, Ala., who are descended from enslaved cotton pickers.

To date, there are no plans by Ms. Harris to commemorate the 34 Black men and women. Their individual histories have all but vanished. The remains of only two have been accounted for.

One of them, Mary Brown, was about 16 at the time of her emancipation and later worked as a housekeeper in Washington before dying in 1886 at the age of 40. The other was Ellen Jenkins, the cook. Ms. Jenkins became a nurse and lived until she was 80.

Both women were buried in a Black cemetery that is now the site of Walter Pierce Park, two miles east of where Ms. Harris lives today.