Africans in AmericaWhen captive Africans first set foot in North America, they found themselves in the midst of a slave society. During most of the 17th and 18th centuries, slavery was the law in every one of the 13 colonies, North and South alike, and was employed by its most prominent citizens, including many of the founders of the new United States. The importation of captives for enslavement was provided for in the U.S. Constitution, and continued to take place on a large scale even after it was made illegal in 1808. The slave system was one of the principal engines of the new nation's financial independence, and it grew steadily until it was abolished by war. In 1790 there were fewer that 700,000 enslaved people in the United States; in 1830 there were more than 2 million; on the eve of the Civil War, nearly 4 million.