The legal institution of human chattel slavery, comprising the enslavement primarily of Africans and African Americans, was prevalent in the United States of America from its founding in 1776 until 1865, predominantly in the South. Slavery was found throughout European colonization in the Americas. From 1526, during the early colonial period, it was practiced in what became Britain's colonies, including the Thirteen Colonies that formed the United States. Under the law, children were born into slavery, and an enslaved person was treated as property that could be bought, sold, or given away. Slavery lasted in about half of U.S. states until abolition in 1865, and issues concerning slavery seeped into every aspect of national politics, economics, and social custom. In the decades after the end of Reconstruction in 1877, many of slavery's economic and social functions were continued through segregation, sharecropping, and convict leasing. Involuntary servitude as a punishment for crime remains legal.
By the time of the American Revolutionary War (1775–1783), the status of enslaved people had been institutionalized as a racial caste associated with African ancestry. During and immediately following the Revolution, abolitionist laws were passed in most Northern states and a movement developed to abolish slavery. The role of slavery under the United States Constitution (1789) was the most contentious issue during its drafting. The Three-Fifths Clause of the Constitution gave slave states disproportionate political power, while the Fugitive Slave Clause (Article IV, Section 2, Clause 3) provided that, if a slave escaped to another state, the other state could not prevent the return of the slave to the person claiming to be his or her owner. All Northern states had abolished slavery to some degree by 1805, sometimes with completion at a future date, and sometimes with an intermediary status of unpaid indentured servitude.
