As Americans observe Black History Month this February, considerable attention is being focused on a single stroke of a pen, 200 years ago. 2008 marks the bicentennial of a law that banned future U.S. participation in the international slave trade. VOA's Ted Landphair reports, that historic measure was the topic of a day-long symposium at the National Archives in Washington.

Many southern cities, including Washington, the nation's capital, had slave pens and auction houses, where Africans were sold like dry goods, and families often separated

Over the span of three centuries, millions of Africans were abducted by slavers, transported in chains to the Americas, and sold as commodities no different than the cotton and sugar and rum then being loaded onto American ships and carried to Europe. Considered subhuman, African slaves became the economic underpinning of the southern U.S. economy.

Howard Dodson, director of New York's Schomburg Center for Research in Black Culture, emphasizes that the slave trade was by no means clandestine. It was aboveboard, completely legal. "All of the activities that people were engaged in were considered to be legitimate economic enterprise,' he notes. "The passage of the law actually raised questions about that in a fundamental way."

Ali Mazrui, a native Kenyan who is a professor of humanities at Binghamton University in New York State, likens the trafficking in humans as chattel to today's terrorism, and the Slave Trade Act as the first assault in a long war on that terror.

Ali Mazrui believes the Slave Trade Act of 1800 was the first salvo in a different war on terror, two centuries ago

"Just as terrorists in our military sense today devalue human life, in those days of enslavement, you might devalue that person and throw [him or her] overboard and then claim insurance," he observes. "On the other hand, enslavement, unlike destruction of people, puts a value on the labor of those who survive. So the ultimate terror is on the other side [of the Atlantic], when people arrive at their destination and spend the rest of their lives captives, and sometimes sold from one slavemaster to another."

In 1807, Britain outlawed transatlantic slaving. A few days earlier, by a surprisingly wide margin, the U.S. Congress had voted to end American participation in the trade. But the American Slave Trade Act did not take effect until the first day of the following year, 1808.

At last, these actions put to paper the notion that enslaving human beings is immoral. Even southern members of Congress supported the measure, not always on ethical grounds. University of Maryland history professor Ira Berlin says the transatlantic trade had outlived its usefulness. "Southern planters, southern slaveholders, now have a labor force that is reproducing itself," he points out. "So they don't need to import slaves."

The southerners also saw the impact of a long, brutal slave insurrection in nearby Haiti, which ousted the French and left thousands of slaveholders massacred. The South had enough problems controlling its existing slaves without bringing in more.

Howard University's Joseph Harris says whites as well as blacks benefit when one of the ugly chapters of American history is reopened for study

Howard University historian Joseph Harris, who organized the National Archives conference, notes that word of the passage of the Slave Trade Act spread quickly among the enslaved in the South. "Many of them developed aspirations, seeing this as making the end of enslavement more imminent than it was," he says. "[It encouraged] the African population in the United States to seek a closer identity with Africa. And that in itself was huge, because the enslavers had done so much to dehumanize African people. You see emerging out of that a more intensified antislavery movement in this country."

And Joseph Harris says the re-examination of the slave trade today has prompted descendants of those involved -- white as well as black -- to reflect on how otherwise thoughtful and rational people could have so blithely engaged in human trafficking. He spent an evening with Thomas DeWolf, who has written a book about an ancestor, a New Englander who was the largest slave trader in America.

Even after the invention of the cotton gin, which sped up the sorting of cotton, field slaves were essential to pick the South's biggest money-making crop

"Several of the people of European descent came to me and said, 'You know, we do have old documents that our family never wanted to talk about. And I'm going to go now and look to see if we can do what the DeWolfs have done,'" he says. "These are things that we need to know about as a part of the way in which our country developed. Then we can communicate better. We don't feel so guilty about withholding what we know happened. Let's address it. Let's get on about the business of being citizens. Let's get on about the business of being human beings.

Despite congressional passage of the Slave Trade Act of 1808, some illegal slaving continued for decades, and naval squadrons were seldom dispatched to seize slave vessels. In the United States, it took a civil war, more than half a century later, to finally put an end to slavery.