SARAH ELIZABETH ADAMS was around 5 when her mother was sold to a slave dealer in Lynchburg, Va. The auction took place in the mid-1840s, in the town of Marion, Va. Sallie, as she was called, was herself sold that day, but not with her mother: A man named Thomas Thurman purchased Sallie to take care of his sick wife. She would never see her mother again. For the remainder of her childhood, whenever she could, Sallie would slip away and find solace under a tall white-oak tree. All alone, she would wrap her arms around the tree’s wide trunk and cry. The tree became the place where she would recall the names and faces of her family members sold away; a place where she could grieve, but also a place where she could find shade and respite from her sorrow.

This story was told many years later by Sallie’s granddaughter, Evelyn Thompson Lawrence, a local educator and historian in Marion. Thompson’s efforts led to the founding of the Mount Pleasant Heritage Museum — housed in a former black Methodist church that Sallie and other freed men and women founded after the Civil War — to preserve the history and culture of African-Americans in the county. We know that Sallie was sold at an auction held at the Smyth County Courthouse, a brick building that was torn down after the turn of the century, when Mari­on’s current courthouse was constructed. And yet many details of her story have been lost: We don’t know exactly what happened to Sallie’s mother, or how much Sallie was sold for, or even exactly when the auction took place.

Sallie and her family were among the 1.2 million enslaved men, women and children sold in the United States between approximately 1760 and 1860, according to the historian Michael Tadman. After the American Revolution, cotton production grew rapidly, and demand for enslaved workers on the vast plantations of the Deep South intensified. This, along with the ban on importation of enslaved Africans that took effect in 1808, largely led to the rapid growth of the domestic slave trade. Auctions and the sales of enslaved people could be found near or along the major ports where enslaved Africans landed, including Richmond, Va.; New Orleans; Savannah, Ga.; and Charleston, S.C. But the enslaved were also sold in Massachusetts, Rhode Island, New Jersey and at New York City’s 18th-century open-air Meal Market on Wall Street. The sales took place all over the growing nation — in taverns, town squares and train stations, on riverbanks and by the side of the road. Before being sold, the enslaved were often kept in pens or private jails, sometimes for days or weeks. Then they were sold directly from the pens or marched to a nearby auction. Thousands of sales took place each year, right in the hearts of American cities and towns, on the steps of courthouses and city halls. As the historian Steven Deyle puts it, slave auctions were “a regu­lar part of everyday life.”