Slavery in the United States

An animation showing when United States territories and states forbade or allowed slavery, 1789–1861

About 600,000 slaves were transported to the United States, or 5% of the twelve million slaves taken from Africa. About 310,000 of these persons were imported into the Thirteen Colonies before 1776: 40% directly and the rest from the Caribbean.

Continental soldiers at Yorktown. On the left, an African American soldier of the 1st Rhode Island Regiment.

In addition, many parts of the country were tied to the Southern economy. As the historian James Oliver Horton noted, prominent slaveholder politicians and the commodity crops of the South had a strong influence on United States politics and economy. Horton said,

None of these ideas got very far, but they alarmed Northerners and contributed to the growing polarization of the country.

Slavery is a volcano, the fires of which cannot be quenched, nor its ravishes controlled. We already feel its convulsions, and if we sit idly gazing upon its flames, as they rise higher and higher, our happy republic will be buried in ruin, beneath its overwhelming energies.

Throughout the first half of the 19th century, abolitionism, a movement to end slavery, grew in strength; most abolitionist societies and supporters were in the North. They worked to raise awareness about the evils of slavery, and to build support for abolition.

Slaveholders began to refer to slavery as the "peculiar institution" to differentiate it from other examples of forced labor. They justified it as less cruel than the free labor of the North.

In Alabama, slaves were not allowed to leave their master's premises without written consent or passes. This was a common requirement in other states as well, and locally run patrols (known to slaves as pater rollers) often checked the passes of slaves who appeared to be away from their plantations. In Alabama slaves were prohibited from trading goods among themselves. In Virginia, a slave was not permitted to drink in public within one mile of his master or during public gatherings. Slaves were not permitted to carry firearms in any of the slave states.

In Ohio, an emancipated slave was prohibited from returning to the state in which he or she had been enslaved. Other Northern states discouraged the settling of free blacks within their boundaries. Fearing the influence of free blacks, Virginia and other Southern states passed laws to require blacks who had been freed to leave the state within a year (or sometimes less time) unless granted a stay by an act of the legislature.

By January 1, 1808, when Congress banned further imports, South Carolina was the only state that still allowed importation of enslaved people. The domestic trade became extremely profitable as demand rose with the expansion of cultivation in the Deep South for cotton and sugar cane crops. Slavery in the United States became, more or less, self-sustaining by natural increase among the current slaves and their descendants. Maryland and Virginia viewed themselves as slave producers, seeing "producing slaves" as resembling animal husbandry. Workers, including many children, were relocated by force from the upper to the lower South.

Illustration from History of American conspiracies – a record of treason, insurrection, rebellion and c., in the United States of America, from 1760 to 1860 (1863)

This rebellion prompted Virginia and other slave states to pass more restrictions on slaves and free people of color, controlling their movement and requiring more white supervision of gatherings. In 1835 North Carolina withdrew the franchise for free people of color, and they lost their vote.

As the great day drew nearer, there was more singing in the slave quarters than usual. It was bolder, had more ring, and lasted later into the night. Most of the verses of the plantation songs had some reference to freedom. ... Some man who seemed to be a stranger (a United States officer, I presume) made a little speech and then read a rather long paper – the Emancipation Proclamation, I think. After the reading we were told that we were all free, and could go when and where we pleased. My mother, who was standing by my side, leaned over and kissed her children, while tears of joy ran down her cheeks. She explained to us what it all meant, that this was the day for which she had been so long praying, but fearing that she would never live to see.

  Gradual emancipation in New York (starting 1799) and New Jersey (starting 1804)
  Effective abolition of slavery by Mexican or joint US/British authority
  Territory incorporated into the U.S. after the passage of the Thirteenth Amendment
An industrial school set up for ex-slaves in Richmond during Reconstruction

African-American history and culture scholar Henry Louis Gates Jr. wrote:

Evolution of the enslaved population of the United States as a percentage of the population of each state, 1790–1860