Article I, Section 9, Clause 1 of the U.S. Constitution (1787) stipulated that "The Migration or Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by the Congress prior to the Year one thousand eight hundred and eight, but a Tax or duty may be imposed on such Importation, not exceeding ten dollars for each Person."

In consequence, the United States abolished its slave trade from Africa, effective January 1, 1808. But slave trading, now illegal, continued unabated until 1860.

The U.S. Slave Trade Act, enacted by a vote of 63 in favor and 49 against in February 1807, was a half victory for the slavers because it specified that the Africans illegally brought to slaveholding states would still be sold and enslaved. Penalties merely consisted of fines. With the authorities turning a blind eye and refusing to enforce their own law, the illegal slave trade flourished for several decades, particularly in Texas (Spanish until 1821), Florida (Spanish until 1818), Louisiana, and South Carolina.

The Suppression of the African Slave-trade to the United States of America 1638-1870 by W.E.B. Du Bois

Africans were sold with little secrecy. As recounted by a slave smuggler, it was an easy task: "I soon learned how readily, and at what profits, the Florida negroes were sold into the neighboring American States. The kaffle [ coffle] . . . [was to] cross the boundary into Georgia, where some of our wild Africans were mixed with various squads of native blacks, and driven inland, till sold off, singly or by couples, on the road."

The introduction of African captives took such proportions that President Madison wrote to Congress: "it appears that American citizens are instrumental in carrying on a traffic in enslaved Africans, equally in violation of the laws of humanity, and in defiance of those of their own country."

Congress passed a tougher law in 1820 making international slave trading an act of piracy punishable by death. Even though the traffic went on, only one American was ever executed for this crime. In addition, American slavers, particularly from New York and Rhode Island, shipped Africans to Cuba, Puerto Rico, and Brazil, where the slave trade was still legal.

Captain Canot or Twenty Years of an African Slaver by Brantz Mayer, editor

More than 3.3 million Africans were transported between 1801 and 1867, the vast majority to Brazil and Cuba. Half came from west-central Africa, and more than 40 percent were originally from the Bights of Benin and Biafra, and Southeast Africa - Mozambique and Madagascar.

In the 1850s, a movement developed in the South to re-open the international slave trade. It was defeated, but the illegal importation of Africans increased between 1850 and 1860, even though the African Squadron, established by the U.S. government in 1843 patrolled the harbors of the African coast.

	Cuban Slaves in England from The Anti-slavery Reporter and Aborigines' Friend
	The Law as Lawbreaker from Afro-Americans in New York Life and History, vol. 20, no. 2 (July 1996) by Robert Trent Vinson

Although their respective countries had officially outlawed the transatlantic slave trade, American and British slavers and traders continued to be openly involved in it, and their activities brought money and work to shipbuilders, crews, insurance companies, and manufacturers of various trade goods, guns, and shackles. Slave ships brought Africans until the Civil War. The Clotilda landed more than a hundred men, women, and children from Benin and Nigeria in the summer of 1860 at Mobile, Alabama. The Wanderer had discharged several hundred people from the Congo on Jekyll Island, Georgia, in November 1858. In both cases, the Africans were sold and enslaved. As a testimony to the persistence of the illegal slave trade, the 1870 Census reveals the presence, in the United States, of numerous men and women born in Africa well after 1808.

	"Oh, What A Tangled Web We Weave": Britain, the Slave Trade and Slavery, 1808 - 43 by Marika Sherwood
	Men and Women Born in Africa from 1870 United States Census
	Africans in the 1880 Census (table)