Yesterday, on Martin Luther King's Birthday, Browne's documentary about her slave-trader ancestors, Traces of the Trade: A Story From the Deep North, premiered at the indie conclave in Park City, Utah.

Nine years in the making, the film, as emotional as it is provocative, is the work of a Philadelphian who grew up "steeped in our country's democratic ideals."

Traces, a chronicle that wags have dubbed "the Caucasian Roots," explores the legacy of the DeWolfs, the dominant American slave-trading dynasty, which flourished from 1769 to 1820.

Though the transatlantic slave trade was outlawed by the United States in 1808, Browne found that the DeWolfs had an executive exemption from President Thomas Jefferson to ply their trade. For the next two decades they intimidated customs agents in Bristol, R.I., into looking the other way. Bristol's economy - built on distilling sugar from Cuba into rum to trade for Africans, and forging leg irons to chain slaves for transport back to North America - depended on it.

Bristol? The city that bills itself as the "most patriotic town in America"? Browne has the home movies of herself as a 3-year-old in a red-striped dress, waving the Stars and Stripes at Bristol's Independence Day Parade, the nation's oldest.

"Little did Dad know to what symbolic purpose his footage would serve," the filmmaker deadpanned, speaking by phone last week from Cambridge, Mass., while packing for Sundance. Browne, 40, begins her documentary with this clip of herself as a child, oblivious to the roots of her family's prosperity and privilege.

The daughter of Stanhope Browne, an attorney, and his wife, Libby, a civic historian and preservationist, the first-time filmmaker grew up in Society Hill, only steps from the Liberty Bell.

"The neighborhood was my classroom," says Browne, who worshipped at St. Peter's Church and attended school there. Of this self-described "cornball for democracy," it would not be a stretch to say that July Fourth is her Christmas.

As she tells it, her maternal grandmother circulated her chronicle of the family history in 1996. It confirmed what Browne "subliminally knew" - that her big-branched family tree grew on the profits from human bondage.

"I was mortified," Browne recalls. "I was a representative of New England's amnesia about slavery." At the time Browne, a Princeton graduate and former AmeriCorps administrator, was in a San Francisco seminary. She felt compelled to tell her family story, but knew she couldn't do it alone.

She invited 200 relatives to join her in retracing the Triangular Trade route that made the DeWolfs rich and powerful. Nine of them came along.

Digital camcorder in tow, they began in Bristol at the imposing family mansion, Linden Place, where Ethel Barrymore, wife of DeWolf scion Russell Colt, once lived.

They set off for Ghana to explore the slave forts where, routinely, as many as 1,300 souls were chained together, wallowing in their own excrement, before their passage to the Americas.

They visited the ruins of DeWolf plantations in Cuba where the sugarcane was harvested to make Rhode Island rum to trade for African slaves.

The more Browne and her kin learned about the family business, the more family pride became family shame. They debated how best to expose the truth of the past and seek reconciliation and reparation in the present.

Should they apologize on behalf of their forebears? What would reparation look like, and what form should it take? Would this attempt to expiate the sins of the forefathers be regarded as an empty exercise in white guilt? Such debates make up the most compelling sequences in Traces.

"It was important to take responsibility as a family," says the soft-spoken Browne. But not every DeWolf descendant, which included Episcopal clergy, was reading from the same hymnal.

"Schism is too strong a word for how the movie affected my family, but, yes, there was and is division about the value of bringing the history up and bringing it forward," she admits.

After a screening of Traces, one of Browne's cousins, Lisa Colt, worried, "I had the sense that Katrina had waded into deep, cold and dark water and left her life raft behind."

But another, Tom DeWolf, who accompanied Browne on the trip, was moved to write a memoir of the journey, Inheriting the Trade, published this month by Beacon Press, in which he talks about the journey as a transformative experience.

"My family directly benefited from inherited privilege," Browne says. To what extent are they culpable for the "equality gap" between black and white today? Browne holds that the DeWolf family's responsibility is to make restitution, spiritual and material, to those who suffered from what she calls "inherited disadvantage."

Britain outlawed slavery in 1807, the year before the slave trade was outlawed in the United States. Last year it commemorated its abolition bicentennial with many events.

"It's mind-boggling . . . that Great Britain spent $40 million and 10 years preparing what they did and [the United States] can't even pass a commemoration bill with 10 cents attached to it," Tom DeWolf told the Denver Post.

Browne would prefer another piece of legislation, one that would enact a truth, repair and reconciliation commission like that in South Africa after the end of apartheid.

"I'm less concerned with understanding the inhumanity of my ancestors," she says, "than with understanding the well-intentioned white folk who are part of systems that still do harm."