In 1991 excavators for a new federal office building in Manhattan unearthed the remains of more than 400 Africans stacked in wooden boxes sixteen to twenty-eight feet below street level. The cemetery dated back to the seventeenth and eighteenth centuries, and its discovery ignited an effort by many Northerners to uncover the history of the institutional complicity with slavery. In 2000 Aetna, one of Connecticut’s largest companies, apologized for profiting from slavery by issuing insurance policies on slaves in the 1850s. After a four-month investigation into its archives, Connecticut’s largest newspaper, the Hartford Courant, apologized for selling advertisement space in its pages for the sale of slaves in the eighteenth and nineteenth centuries. And in 2004 Ruth Simmons, president of Brown University, established the Steering Committee on Slavery and Justice to investigate “and discuss an uncomfortable piece” of the university’s history: The construction of the university’s first building in 1764, reads a university press release, “involved the labor of Providence area slaves.”

Now another blue-blooded institution–the New-York Historical Society–has joined this important public engagement with our past by mounting an ambitious exhibition, “Slavery in New York.” To all those who think slavery was a “Southern thing,” think again. In 1703, 42 percent of New York’s households had slaves, much more than Philadelphia and Boston combined. Among the colonies’ cities, only Charleston, South Carolina, had more.

The history presented here does not offer the flabby reflection that “slavery is bad” or that once it came to an end everyone lived happily ever after. The Historical Society hired experts led by Richard Rabinowitz, historian and president of the American History Workshop, to untangle the complicated stories of slavery and provide historical context. With more than a score of scholarly advisers weighing in, one wonders whether there were too many cooks, each one bringing a different feature of slavery at the expense of some themes that cry out for explication.

Take, for example, the creation of a distinctive black community of “half-free” New Yorkers in the middle of what is today’s downtown but well north of the cluster of seventeenth-century houses. “Slavery in New York” leaves the designation “half-free” dangling suggestively, unexplored and undefined. Wasn’t slavery straightforward? How could someone be enslaved and free? Fortunately, a book of essays titled Slavery in New York, published in conjunction with the New-York Historical Society, provides a valuable supplement to the exhibit (and a worthwhile resource in its own right). The collection–co-edited by Ira Berlin, a distinguished scholar of slavery, and Leslie M. Harris, the author of a 2003 study of slavery in New York (The Shadow of Slavery)–assembles a prodigious group of scholars, writing on topics ranging from slave rebellion, slavery in the American Revolution, black abolitionism and life after slavery.

Half-free, we learn from Berlin and Harris’s introduction, reflected the evolving nature of slavery in the urban North. The Dutch West India Company that governed New Amsterdam worked its chattel hard, clearing the land, splitting logs, milling lumber and building wharves, roads and fortifications; but slavery was so ill defined in those days that slaves collected wages. In 1635, when wages were not forthcoming, a small group petitioned the company for redress, and that’s when they became “half-free.” As a condition of their half-freedom, families who sustained themselves as farmers agreed to labor for the company when it called on them and pay an annual tribute in furs, produce or wampum. This arrangement provided the company with a loyal reserve force without the responsibility for supporting its workers. It was less beneficial for the half-free men and women. Their status was not automatically passed down to their children, who instead remained the property of the company. This anomalous sorting of humanity produced an ongoing struggle over freedom, and it reflected “the ambiguous place of black men and black women in New Netherland. Exploited, enslaved, unequal to be sure,” write Berlin and Harris, “they were recognized as integral, if inferior, members of the Dutch colony on the Hudson.” And their status conferred on them a penchant to make trouble.

A map titled “Landscapes of Conspiracy” shows Hughson’s Tavern, where black and white New Yorkers intermingled. There they “drank, divvied up stolen goods, [and] slept together,” reads the label. Hughson’s was on the far west side of the city, where Crown Street intersected with today’s West Side Highway. The map details New Amsterdam in 1741, a crucial year in the city’s history of slavery. After an especially severe winter, ten fires blazed in the city over three short weeks. A grand jury called by the Supreme Court quickly concluded that the fires were the work of black arsonists, “plot Negroes” from the half-free community. They were accused of acting as part of a vast conspiracy that seemed to involve just about every slave in the city and was carefully planned by John Ury, an “alleged” white priest, and John Hughson. It seems that the Supreme Court Justice was unwilling to believe that black people could have devised the plot themselves. In an admirable essay in the accompanying volume, the historian Jill Lepore argues there was little evidence to support the Ury-Hughson plot. As to the question of whether there actually had been a plot, Lepore says the evidence is inconclusive. What is clear, she argues, is that given a history of the city’s slave codes (which serve as a record of the difficulty of enslaving human beings) and the testimony of the slaves themselves, “much evidence points to a plot hatched on street corners and in markets, the forging of an Akan-influenced brotherhood” and “a political order that encouraged individual acts of vengeance, of cursing whites and setting fires, skirmishes in the daily, unwinnable war of slavery.”

One of the many strengths of “Slavery in New York” is its depiction of American history and life that was (and is) entangled with other histories and other lives. It puts to rest any mistaken belief that globalization began recently with outsourcing and free-trade agreements. The profits from the slave trade and products of slave labor, the exhibition tells us, “fueled the world’s first industrial revolution.” By 1800 it also fueled moral outrage against slave trading, igniting “the first international human rights movement,” another suggestive comment left undeveloped. It turns out this is the subject of a second exhibition slated for next year.

On display is The Trading Book of the Sloop of Rhode Island, which left the Port of New York in 1748 for West Africa under the direction of Capt. Peter James. Thumbing through a virtual trading book while the original remains safely behind glass, the visitor will see that early in the voyage, around Sierra Leone, James distributed two New World commodities that had come through the Port of New York: tobacco and rum, connecting the British colonies of Virginia and Caribbean plantation economies into an Atlantic world of inebriation and addiction. In return he loaded up on cloth, guns and other manufactured goods from Europe. Later, as he sailed along the Gold Coast (today’s Ghana), he traded those goods for slaves, a few at a time.

James’s book registered the deaths of thirty-eight slaves on the journey home. But even with the loss, the trafficking in slaves was profitable. A table provides a graphic illustration of just how lucrative the business was. In 1675 the average selling price of a slave in dollars in Africa was $354.89, and in New York it was $3,792.66 (that’s a 969 percent markup, for those econometricians keeping score). A hundred years later the trade was still profitable, although with a more modest return of 159 percent.

“Slavery in New York” is not the last word on how the institution evolved–and how it helped New York develop into the most powerful port in the hemisphere in the decades after New York State’s Gradual Emancipation Law of 1799. When you walk down a hallway at the end of the exhibition, pause to ponder two quotes inscribed on the wall, both written years after the abolition of slavery in all of the Americas. The first is by U.B. Phillips, grandson of a Southern planter and a historian who wrote favorably about slavery in 1929, and the other is by W.E.B. Du Bois, scholar, polemicist and pan-Africanist who recognized before anyone else that slavery, even when it was confined to the South in the years before the Civil War, was a national phenomenon that touched the lives of every American, black, white, slave and free. It seems right that Du Bois should have the last word in “Slavery in New York.”