There were almost 700 thousand slaves in the US in 1790, which equated to approximately 18 percent of the total population, or roughly one in every six people. By 1860, the final census taken before the American Civil War, there were four million slaves in the South, compared with less than 0.5 million free African Americans in all of the US. Of the 4.4 million African Americans in the US before the war, almost four million of these people were held as slaves; meaning that for all African Americans living in the US in 1860, there was an 89 percent* chance that they lived in slavery. A brief history Trans-Atlantic slavery began in the early sixteenth century, when the Portuguese and Spanish forcefully brought captured African slaves to the New World, in order to work for them. The British Empire introduced slavery to North America on a large scale, and the economy of the British colonies there depended on slave labor, particularly regarding cotton, sugar and tobacco output. In the seventeenth and eighteenth century the number of slaves being brought to the Americas increased exponentially, and at the time of American independence it was legal in all thirteen colonies. Although slavery became increasingly prohibited in the north, the number of slaves remained high during this time as they were simply relocated or sold from the north to the south. It is also important to remember that the children of slaves were also viewed as property, and (apart from some very rare cases) were born into a life of slavery. Abolition and the American Civil War In the years that followed independence, the Northern States began gradually prohibiting slavery, and it was officially abolished there by 1805, and the importation of slave labor was prohibited nationwide from 1808 (although both still existed in practice after this). Business owners in the Southern States however depended on slave labor in order to meet the demand of their rapidly expanding industries, and the issue of slavery continued to polarize American society in the decades to come. This culminated in the election of President Abraham Lincoln in 1860, who promised to prohibit slavery in the newly acquired territories to the west, leading to the American Civil War from 1861 to 1865. Although the Confederacy (south) were victorious in much of the early stages of the war, the strength in numbers of the northern states (including many free, black men), eventually resulted in a victory for the Union (north), and the nationwide abolishment of slavery with the Thirteenth Amendment in 1865. Legacy In total, an estimated twelve to thirteen million Africans were transported to the Americas as slaves, and this does not include the high number who did not survive the journey (which was as high as 23 percent in some years). In the 150 years since the abolishment of slavery in the US, the African-American community have continuously campaigned for equal rights and opportunities that were not afforded to them along with freedom. The most prominent themes have been the Civil Rights Movement, voter suppression, mass incarceration and the relationship between the police and the African-American community has taken the spotlight in recent years.

Between 1628 and 1860, it is estimated that almost 390 thousand Africans were transported as slaves to European colonies in Mainland North America. This figure refers only to those who survived the journey, as it is also thought that over 470 thousand captives embarked on these ships at African ports, however 84 thousand died en route (giving a mortality rate of 17.7 percent). The transportation of African slaves to the Thirteen Colonies was highest in the mid-18th century (although there was some fluctuation), before an observable decline around the time of the American Revolutionary War. Following independence, the importation of slaves remained lower than in previous decades, until it saw a sharp increase in the five years leading up to the slave trade's abolition. In 1807 alone, the year before the U.S. abolished the slave trade, almost 29 thousand slaves were imported from Africa into the U.S. Following this, activity declined greatly; the relatively small number of slaves imported from Africa to the U.S. were most likely into the Spanish territory of Florida. Smuggling also existed on a smaller scale; this accounts for the entries in 1858 and 1860.

At the beginning of the 19th century, the U.S. labor force was approximately 1.9 million people, with slaves making up over half a million (28 percent) of this number. The share of slaves then increased to almost one third of the overall workforce in the next decade, but dropped to roughly one fifth by 1860; the year before the American Civil War. While the total number of slaves grew by several hundred thousand in each decade, their share of the U.S. labor force decreased due to the high levels of European migration to the U.S. throughout the 19th century. This wave of mass migration was an influential factor in slavery's eventual abolition, as Europeans met the labor demands that had previously been fulfilled by slaves, and those fleeing persecution and oppression in Europe were often sympathetic to the plight of slaves. Nonetheless, the majority of European migrants arrived in the industrialized, northern states, most of which had already abolished slavery in the 18th century, and slave labor was concentrated in the agricultural south at this time; this divide would prove fundamental in the outbreak of the American Civil War.

The issue of race and slavery was arguably the largest cause of the American Civil War, with the southern states seceding from the Union as the practice of slavery became increasingly threatened. From the graph we can see that roughly 16.5 percent of the entire US population at this time was black, and the vast majority of these were slaves. In 1860 there were almost 27 million white people, four and a half million black people, and less than one hundred thousand non-black or white people (mostly of Native/Latin American or East-Asian origin).

This statistic shows the number of black men and women in the US from 1820 until 1880. Slavery was legal in the Southern States of the US until 1865, when the Thirteenth Amendment was added to the US Constitution after the American Civil War. Until that time all of the slaves included in this statistic were registered as living in the South, whereas the majority of the free, black men and women lived in the Northern States. From the data we can see that, while the slave experience was very different for men and women, there was relatively little difference between their numbers in each respective category. While female slaves were more likely to serve in domestic roles, they were also more likely to be working in the lowest and unskilled jobs on plantations, whereas men were given more skilled and physically demanding roles. As slavery was abolished in 1870, all black people from this point were considered free in the census data. It is also worth noticing that in these years the difference in the number of men and women increased, most likely as a result of all the black male soldiers who fell fighting in the American Civil War.

Estimates of captives carried in the Atlantic slave trade by decade, 1650s to 1860s. Data: routes of voyages and recorded numbers of captives (10 variables and 33,345 cases of slave voyages). Data are organized into 40 routes linking African regions to overseas regions. Purpose: estimation of missing data and totals of captive flows. Method: techniques of Bayesian statistics to estimate missing data on routes and flows of captives. Also included is R-language code for simulating routes and populations

This statistic shows the population of the United States in the final census year before the American Civil War, shown by race and gender. From the data we can see that there were almost 27 million white people, 4.5 million black people, and eighty thousand classed as 'other'. The proportions of men to women were different for each category, with roughly 700 thousand more white men than women, over 100 thousand more black women than men, and almost three times as many men than women in the 'other' category. The reason for the higher male numbers in the white and other categories is because men migrated to the US at a higher rate than women, while there is no concrete explanation for the statistic regarding black people.

From the sixteenth to the mid-nineteenth centuries, Portuguese and Brazilian traders were responsible for transporting the highest volume of slaves during the transatlantic slave trade. It is estimated that, of the 12.5 million African slaves captured during this time, more than 5.8 million were transported in ships that sailed under the Portuguese and, later, Brazilian flags. British traders transported the second-highest volume of slaves across the Atlantic, totaling at almost 3.3 million; over 2.5 million of these were transported in the 18th century, which was the highest volume of slaves transported by one nation in one century.

This data collection contains information about the population of each county, town, and city of the United States in 1850 and 1860. Specific variables include tabulations of white, black, and slave males and females, and aggregate population for each town. Foreign-born population, total population of each county, and centroid latitudes and longitudes of each county and state were also compiled. (Source: downloaded from ICPSR 7/13/10)

Please Note: This dataset is part of the historical CISER Data Archive Collection and is also available at ICPSR -- https://doi.org/10.3886/ICPSR09424.v2. We highly recommend using the ICPSR version as they made this dataset available in multiple data formats.

Between the 17th and mid-19th centuries, almost 400 thousand slaves arrived in mainland North America, after embarking on slave ships in Africa. The most common disembarking regions were in the Carolinas and Georgia, where more than half of these slaves disembarked. The majority of the remaining slaves disembarked in the Chesapeake region, which stretched from Virginia to New York, while a smaller number disembarked further to the north, or in the states along the Gulf of Mexico. It may also be of note that very few slaves disembarked in Chesapeake or the northern U.S. in the nineteenth century, as slavery began to be abolished in some northern states and regions in the late 1700s.

This study presents 1860 data on population and farm production in 5,228 farms located in 405 major cotton-producing counties in the South. The data was compiled from the agriculture, slave, and population schedules of the 1860 United States manuscript Census. For each farm, variables describing farm land, machinery, crops, and livestock are included, as well as production figures for specific crops and types of livestock on the farm. The population variables tabulate the free and slave residents of each farm by sex, race, and age in five- or ten-year categories. This data set contains information of farm production and population residing on farms in the major cotton producing counties of the southern United States. Variables include: county code number; soil type in county; no. farms sampled in county; detailed commodity production of each farm, including acreage, value of farm and machinery, numbers of head of livestock, value of livestock, production of field crops, value of orchard products, wine production, value of market garden products, production of dairy products, production of 'textile' crops, value of home manufactures, value of animals slaughtered; numbers of farm residents by age categories, sex, and status, including free, slave, farm laborer, overseer, non-farm worker.

Lincoln's election produced Southern secession, war, and abolition. Using a new dataset on slave sales, we examine connections between news and slave prices for the period 1856-1861. By August 1861, slave prices had declined by roughly one-third from their 1860 peak. That decline was similar for all age and sex cohorts and thus did not reflect expected emancipation without compensation. The decision to secede reflected beliefs that the North would not invade and that emancipation without compensation was unlikely. Both were encouraged by Lincoln's conciliatory tone before the attack on Fort Sumter, and subsequently dashed by Lincoln's willingness to wage all-out war. (JEL D72, D74, D83, G14, H77, N31, N41)

As part of the Telling All of Our Stories project, Oatlands created a dataset to record every reference to a named enslaved person. The goal was to provide a source for locating ancestors or certain individuals and learning more about the people who were enslaved at Carter plantations Oatlands and Bellefield in Virginia. The first phase consists of names extracted from George Carter's will, written in 1842, and Elizabeth O. Carter's diary, kept from 1860 through 1873. The database contains over 900 entries, and there are approximately 120 distinctly different names. Information from or questions raised by Oatlands researchers are recorded in the Notes column. “List of slave expenditures kept by B. Grayson,” part of a Works Progress Administration Historical Inventory Project conducted in 1937, also provided some details for the dataset.

Between 1775 and 1841, the population of Cuba grew to almost six times its size, from approximately 170 thousand people to over one million. During these years, Cuba was a Spanish colony, where slavery remained legal. In 1841, slaves counted for almost 45% of the total population.

Sugar industry A large reason for this growth was the emergence of the sugar industry, as production was relocated from areas of the Caribbean where slavery was abolished (most notably Haiti in 1804 and Jamaica in 1834). Although Cuba had been a Spanish colony for almost three centuries before these figures begin, it was economically isolated and trade with other nations was restricted; following a brief occupation by the British in the 1860s, international trade became encouraged, and a slave-based plantation complex emerged. By the middle of the 19th century, Cuba had established itself as the largest producer of sugar in the world (a position that it held until the mid-20th century), with the U.S. as it's primary consumer.

Gender differences From the figures for 1827 and 1841, the disparities between the male and female populations become apparent. Males migrated to the Americas at a much higher rate than females, while African males were also captured and enslaved at a higher rate than females during the Atlantic slave trade. This is reflected in the slave and white populations, although the difference within the slave population is much greater. Conversely, among free people of color, the female population population is actually higher than the number of males; this was due to a number of reasons, such as higher rates of manumission among females (the ratio of female to male manumissions was estimated to be around 3:2 in the Caribbean in the 19th century) and higher life expectancy.

This dataset provides four estimates of captive embarkations by region and by decade, 1650s to 1860s, using multiple-methods and Markov Chain Monte Carlo methods. Calculations performed by Yun Zhang, June - August 2013. One of five appendices to the source article.

Brazil conducted its first nationwide census in 1872, just 16 years before slavery's official abolition in 1888. Modern estimates place Brazil's total population in 1872 at approximately 10.3 million; the exclusion of non-white infants and indigenous populations from the census is likely the cause of this deficit. The 1872 census showed that non-whites made up the majority of Brazil's population at this time, at roughly 5.75 million, compared to the white population of 3.79 million. Of these 5.75 million, over 4.2 million were free, compared to 1.5 million living in slavery; this gives a ratio of almost three free non-whites for every one slave. To compare, in the United States in 1860, there were at least eight slaves for every one free person of color in the years leading up to slavery's nationwide abolition.

From 1501 until 1866, it is estimated that the transatlantic slave trade saw more than 12.5 million African people forcefully put on slave ships and transported to the Americas. Of these 12.5 million, only 10.7 million disembarked on the other side of the Atlantic, meaning that approximately 1.8 million (14.5 percent) did not survive the journey, known as the Middle Passage. Throughout most of the the sixteenth century, the mortality rate was around thirty percent, it then fell below twenty percent in the late seventeenth century, and below fifteen percent in the late eighteenth century. There was a slight increase in the mid-1800s, before the transatlantic slave trade effectively ended in the 1860s. The overall average mortality rate is lower than the rate in most decades, due to the larger numbers of captives transported in the late 1700s; a significant number of these voyages were between Africa and Brazil, which was generally the shortest of the major routes.

This dataset provides estimates of captive arrivals in the Americas by region and by decade, 1650s to 1860s, using Markov Chain Monte Carlo method. Calculations performed by Bowen Yi, June - August 2015. One of five appendices to the source article. Table 2A presents results of MCMC analysis of captive arrivals.

Sumner, Charles, 1811-1874, compiler. Volume I. Fugitive slaves : scrapbook of clippings, 1850-1860., 1850-1860.

Of the first eighteen presidents of the United States, twelve owned slaves throughout their lifetime, and eight of these were slave owners while occupying the office of president. Of the U.S.' first twelve presidents, the only two never to own slaves were John Adams, and his son John Quincy Adams; the first of which famously said that the American Revolution would not be complete until all slaves were freed. George Washington, leader of the revolution and the first President of the United States, owned many slaves throughout his lifetime, with 123* at the time of his death. Historians believe that Washington's treatment of his slaves was typical of slaveowners in Virginia at the time, however he did develop moral issues with the institution of slavery following the revolution. Washington never publicly expressed his growing opposition to slavery, although he did stipulate in his will that all his slaves were to be freed following the death of his wife, and he made financial provisions for their care that lasted until the 1830s.

Jefferson controversies

In recent years, the legacy of Thomas Jefferson has come under the most scrutiny in relation to this matter; the man who penned the words "all men are created equal" is estimated to have owned at least 600 slaves throughout the course of his lifetime. Before becoming president, Jefferson argued for restrictions on the slave trade, and against its expansion into new US territories; however he avoided the subject during his presidency as the topic grew in divisiveness and he believed that emancipation would not be achieved during his lifetime. It is also widely accepted that Jefferson had an affair and likely fathered children with one of his slaves, Sally Hemmings, who is also believed to be the half-sister of Jefferson's first wife. DNA tests conducted in the 1990s confirmed a genetic link between the descendants of the Jefferson and Hemings families, but could not confirm whether the link was Jefferson himself or a relative; most historians however, believe that Jefferson fathered at least one of Sally Hemings' children, and possibly six or eight of them (all of whom were kept as Jefferson's slaves).

Other Presidents

Of the other presidents who appear on this list, all are regarded differently for their attitudes towards slavery, and their impact on the eventual abolition of slavery and the emancipation of slaves. Madison and Monroe grew up in slave-owning families, and owned a number of slaves while serving in the White House; interestingly, Monrovia, the capital city of Liberia (the country was founded by the American Colonization Society as an African settlement for freed slaves), was named in Monroe's honor as he was a prominent advocate of the ACS. Andrew Jackson, who earned a large portion of his private wealth via the slave trade, introduced legislation that protected slave owners and slavery in the southern states; he owned around 200 slaves at the time of his death, and many more throughout his lifetime. John Tyler publicly decried slavery and claimed that it was evil, although he owned slaves as he said this and his political actions in his later life actually supported the institution of slavery (Tyler is notably the only U.S. president whose death was not mourned officially as he was involved in the government of the Confederacy at the time).

Perhaps the most surprising names on this list are Andrew Johnson and Ulysses S Grant, the vice president and leader of the United States Army during the latter stages of the American Civil War. Neither men owned slaves while in office, although Johnson, the man who oversaw the ratification of the Thirteenth Amendment, is reported to have owned eight slaves before entering the world of politics. Ulysses S. Grant, who managed his wife's family's farm in the 1850s, inherited one slave in 1854 who he then freed two years later. Grant's armies would eventually free countless slaves in the 1860s, as he led the Union to victory against the Confederacy and brought an end to slavery in the United States.