Slavery in the Unite States began soon after English colonists first settled Virginia and lasted until the passage of the Thirteenth Amendment to the United States Constitution. 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. In part because of the Southern colonies' devotion of resources to tobacco culture, which was labor intensive, by the end of the 17th century they had a higher number and proportion of slaves than in the north.