Slavery in the United States began soon after English colonists first settled Virginia in 1607 and lasted as a legal institution until the passage of the Thirteenth Amendment to the United States Constitution in 1865. Before the widespread establishment of chattel slavery, much labor was organized under a system of bonded labor known as indentured servitude. This typically lasted for several years for white and black alike, and it was a means of using labor to pay the costs of transporting people to the colonies. By the 18th century, court rulings established the racial basis of the American incarnation of slavery to apply chiefly to Black Africans and people of African descent, and occasionally to Native Americans. A 1705 Virginia law stated slavery would apply to those peoples from nations that were not Christian. In part because of the success of tobacco as a cash crop in the Southern colonies, its labor-intensive character caused planters to import more slaves for labor by the end of the 17th century than did the northern colonies. The South had a significantly higher number and proportion of slaves in the population. Religious differences contributed to this geographic disparity as well.
From 1654 until 1865, slavery for life was legal within the boundaries of much of the present United States. Most slaves were black and were held by whites, although some Native Americans and free blacks also held slaves; there were a small number of white slaves as well. The majority of slaveholding was in the southern United States where most slaves were engaged in an efficient machine-like gang system of agriculture. According to the 1860 U.S. census, nearly four million slaves were held in a total population of just over 12 million in the 15 states in which slavery was legal. Of all 8,289,782 free persons in the 15 slave states, 393,967 people (4.8%) held slaves, with the average number of slaves held by any single owner being 10. The majority of slaves were held by planters, defined by historians as those who held 20 or more slaves. Ninety-five percent of black people lived in the South, comprising one-third of the population there, as opposed to 2% of the population of the North. The wealth of the United States in the first half of the 19th century was greatly enhanced by the labor of African Americans.