Among the first documented Africans in British North America were approximately 20 men and women who arrived at Jamestown, Virginia, in 1619. They were captives, likely from the kingdom of Ndongo in present-day Angola. Privateers had seized them from a slave ship bound for Mexico and traded them in Virginia. The Africans worked the tobacco fields in Jamestown alongside white indentured servants, but it is not clear if they were considered slaves.
Overview of the Transatlantic Slave Trade, 1501–1867. Yale University Press
By 1700 there were 27,817 enslaved Africans in British North America. In 1740, there were 150,024. By 1770, the number of slaves had grown to 462,000, about one-fifth of the total colonial population.