The modem slave trade, involving the importation of captive Africans to the shores of the New World, began in 1517. Spaniards immigrating to the New World were allowed to import 12 Africans each. The decision to meet the growing labor demands in the new European colonies in the West Indies and South America by using slaves encouraged the fairly rapid development of the trade. Royal monopolies were granted for control of the trade and over the next 200 years, control shifted among Dutch, Portuguese, French and English trading companies and independent traders. The defeat of the Dutch and French in a series of conflicts gave English traders control of the slave trade by the early eighteenth century.

The growing English colonies in America faced a constant labor shortage, which they tried to address by using white and Native American indentured servants, who were contracted to servitude for a limited amount of time. Additionally, some Native Americans were enslaved. In 1619, a Dutch frigate brought 20 Africans to Jamestown, Virginia; they came as indenture servants. However, the use of African indentured servants ended by the 1640s. Indentured servitude proved an insufficient source of labor: there simply weren’t enough whites, blacks and Native Americans in the colonies willing to replace those whose contracts expired. Native American slavery was also a huge failure for the colonists. By the mid-17th century the English colonists had settled on importing Africans as "perpetual servants" for a number of reasons: they looked different, which made finding runaway slaves easier; they did not have long-standing tribes and nations to disappear into, as did Native Americans; and patterns of prejudice against dark-skinned people already existed, which allowed whites to justify their enslavement of another people.

 

By the early 18th century, most of the 13 colonies had accepted slavery and enacted a series of laws, called slave codes, to regulate and protect the slave system. These codes determined rules for conduct between the races and helped legitimate the system.

The huge influence of the Puritans on life in New England, combined with the prevalence of small scale farms (for which slavery was financially impractical), produced religious and economic pressures against the slave system in New England. However, the huge shipping industry in New England, centered in Massachusetts and Rhode Island, provided many of the ships for the 18th century slave trade. In a similar fashion, the anti-slavery beliefs of the Quakers prevented the large-scale growth of slavery in Pennsylvania. It was on the tobacco and rice plantations in the Southern states of Virginia, Maryland, the Carolinas, and after 1750, Georgia that the system had the deepest roots. Economic success in those colonies provided a strong force that resisted religious or intellectual objections to the slave system.

 

By the time of the American Revolution there were almost 750,000 blacks in the 13 colonies, most of them slaves and most located in the Southern colonies.

During the War there was much debate on whether enlisting in the Continental Army meant automatic freedom for slaves. Some colonial legislatures prohibited blacks from fighting just to avoid this issue. In the fifteen-year period after the War the New England states, Pennsylvania, New York and New Jersey, abolished slavery and prohibited the slave trade. However, during the Constitutional Conventional of 1787, Congress protected slavery in the United States Constitution in three ways: by declaring that, for the purposes of taxation and representation, five blacks equaled three whites; by requiring the return of runaway slaves; and by forbidding Congress to debate the abolition of the slave trade for 20 years. Slavery was not abolished in the United States until 1863, when Abraham Lincoln issued the Emancipation Proclamation, freeing all the slaves in the Confederacy.