Slave states and free states
In the United States before 1865, a free state was a state in which slavery and the internal or domestic slave trade were prohibited, while a slave state was one in which they were legal. Between 1812 and 1850, it was considered by the slave states to be politically imperative that the number of free states not exceed the number of slave states, so new states were admitted in slave–free pairs. There were, nonetheless, some slaves in most free states up to the 1840 census, and the Fugitive Slave Clause of the U.S. Constitution, as implemented by the Fugitive Slave Act of 1793 and the Fugitive Slave Act of 1850, provided that a slave did not become free by entering a free state and must be returned to their owner. Enforcement of these laws became one of the controversies that arose between slave and free states.
By the 18th century, slavery was legal throughout the Thirteen Colonies, but at the time of the American Revolution, rebel colonies started to abolish the practice. Pennsylvania abolished slavery in 1780, and about half the states had abolished slavery by the end of the Revolutionary War or in the first decades of the new country's existence, although, depending on the jurisdiction, this did not mean that all slaves became immediately free due to gradual abolition. Vermont — having declared its independence from Britain in 1777 and thus not being one of the Thirteen Colonies — banned slavery in the same year, before being admitted as a state in 1791.
Slavery was a divisive issue in the United States. It was a major issue during the writing of the U.S. Constitution in 1787, the subject of political crises in the Missouri Compromise of 1820 and the Compromise of 1850, and it was the primary cause of the American Civil War in 1861. Just before the Civil War, there were 19 free states and 15 slave states. The most recent free state, Kansas, had entered the Union after its own years-long bloody fight over slavery. During the war, slavery was abolished in some of the slave states, and the Thirteenth Amendment to the United States Constitution, ratified in December 1865, abolished chattel slavery throughout the United States.
History
Early history
was established as a legal institution in each of the Thirteen Colonies, starting in 1619 with the arrival of "twenty and odd" enslaved Africans in Virginia. Although indigenous peoples were also sold into slavery, the vast majority of the enslaved population consisted of Africans brought to the Americas via the Atlantic slave trade. Due to a lower prevalence of tropical diseases and better treatment, the enslaved population in the colonies had a higher life expectancy than in the West Indies and South America, leading to a rapid increase in population in the decades prior to the American Revolution. Organized political and social movements to abolish slavery began in the mid-18th century. The sentiments of the American Revolution and the promise of equalityevoked by the Declaration of Independence stood in contrast to the status of most Black people, either free or enslaved, in the colonies. Despite this, thousands of Black Americans fought for the Patriot cause for a combination of reasons. Thousands also joined the British, encouraged by offers of freedom such as the Philipsburg Proclamation.In the 1770s, enslaved Black people throughout New England began sending petitions to northern legislatures demanding freedom. Five Northern states adopted policies to at least gradually abolish slavery: Pennsylvania in 1780, New Hampshire and Massachusetts in 1783, and Connecticut and Rhode Island in 1784. The Republic of Vermont had limited slavery in 1777, while it was still independent before it joined the United States as the 14th state in 1791. These state jurisdictions thus enacted the first abolition laws in the Atlantic World. By 1804, all the Northern states had abolished slavery or set measures in place to gradually abolish it, although there were still hundreds of ex-slaves working without pay as indentured servants in Northern states as late as the 1840 census.
In the South, Kentucky was created as a slave state from Virginia, and Tennessee was created as a slave state from North Carolina. By 1804, before the creation of new states from the federal western territories, the number of slave and free states was eight each. By the time of Missouri Compromise of 1820, the dividing line between the slave and free states was called the Mason-Dixon line, with its westward extension being the Ohio River.
The 1787 Constitutional Convention debated slavery, and for a time slavery was a major impediment to passage of the new constitution. As a compromise, slavery was acknowledged but never mentioned explicitly in the Constitution. The Fugitive Slave Clause, Article 4, section 2, clause 3, for example, refers to a "Person held to Service or Labor." In addition, Article 1, section 9, clause 1 of the Constitution prohibited Congress from abolishing the importation of slaves, but in a compromise, the prohibition could be lifted by Congress in 20 years, and slaves were referred to as "Persons." The Act Prohibiting Importation of Slaves passed easily in 1807 and took effect on January 1, 1808. However, the ban on importation spurred an expansion in the domestic slave trade, which remained legal until slavery was banned entirely in 1865 by the 13th Amendment.
In the late 1850s, several Southern states launched an unsuccessful campaign to resume the international slave trade, in order to restock their slave populations, but this met with strong opposition. However, a large natural increase in the slave population occurred throughout the late 18th and 19th centuries, while some illegal smuggling of African slaves continued via Spanish Cuba.
Another compromise in the Constitution was the Three-Fifths Clause, by which slave states acquired representation in the House of Representatives and Electoral College equivalent to 60 percent of their disenfranchised slave populations. Slave states had wanted 100 percent of their slaves to be counted, whereas Northern states argued that none should be, because, as Elbridge Gerry said, why should "blacks, who were property in the South", count toward representation "any more than the Cattle & horses of the North"?
New Territories
The Northwest Ordinance of 1787, passed just before the U.S. Constitution was ratified, had prohibited slavery in the federal Northwest Territory. The southern boundary of the territory was the Ohio River, which was regarded as a westward extension of the Mason-Dixon line. The territory was generally settled by New Englanders and American Revolutionary War veterans who were granted land there. The 6 states created from the territory were all free states: Ohio, Indiana, Illinois, Michigan, Wisconsin, and Minnesota.By 1815, the momentum for anti-slavery reform appeared to run out of steam, with half the states having already abolished slavery, prohibited it from the start, or committed to eliminating it, and half committed to continuing the institution indefinitely.
The potential for political conflict over slavery at the federal level made politicians concerned about the balance of power in the Senate, where each state was represented by two senators. With an equal number of slave states and free states, the Senate was equally divided on issues important to the South. As the population of the free states began to outstrip the population of the slave states, leading to control of the House of Representatives by free states, the Senate became the preoccupation of slave-state politicians interested in maintaining a congressional veto over federal policy with regard to slavery and other issues important to the South. As a result of this preoccupation, slave states and free states were often admitted into the Union in opposite pairs to maintain the existing Senate balance between slave and free states.
Missouri Compromise
Controversy over whether Missouri should be admitted as a slave state resulted in the Missouri Compromise of 1820, which specified that territory acquired in the Louisiana Purchase north of latitude 36° 30', which described most of Missouri's southern border, would, except for Missouri, become free states, and territory south of that line would become slave states. As part of the compromise, Maine, on August 19, 1821, was admitted as a free state.Texas and the Mexican Cession
The admission of Texas as a slave state in 1845 and the acquisition of the vast new Mexican Cession territories in 1848, after the Mexican–American War, created further north–south conflict. Anglo-American settlers brought slaves to Mexican Texas, and though Mexico outlawed slavery in most of its territories in 1829, Texas was granted an exemption. The settled portion of Texas was an area rich in cotton plantations and dependent on slave labor, while the territory acquired in the Mountain West did not seem hospitable to cotton or slavery.As part of the Compromise of 1850, California was admitted as a free state. After Oregon was admitted as a free state in 1859, there were no slave states on the Pacific coast. To avoid creating a free state majority in the Senate, California was forced to send one pro-slavery and one anti-slavery senator to Congress.
Last battles
The difficulty of identifying territory that could be organized into additional slave states stalled the process of opening the western territories to settlement. Slave-state politicians made efforts to annex Cuba and Nicaragua, with intentions to create new slave states. Parts of Northern Mexico were also coveted, with Senator Albert Brown declaring "I want Tamaulipas, Potosi, and one or two other Mexican States; and I want them all for the same reason – for the plantation and spreading of slavery".Kansas
In 1854, the Missouri Compromise of 1820 was superseded by the Kansas–Nebraska Act, which allowed white male settlers in the new territories to determine, by vote, whether they would allow slavery within each territory. The result was that pro- and anti-slavery elements flooded into Kansas with the goal of voting slavery up or down, leading to bloody fighting. An effort was initiated to organize Kansas for admission as a slave state, paired with Minnesota, but the admission of Kansas as a slave state was blocked because its proposed pro-slavery constitution had not been approved in an honest election. Anti-slavery proponents during the "Bleeding Kansas" period of the later 1850s were called Free-Staters and Free-Soilers and fought against pro-slavery Border Ruffians from Missouri. The animosity escalated throughout the 1850s, culminating in numerous skirmishes and devastation on both sides of the question. Nevertheless, the North prevented Kansas Territory from becoming a slave state, and when Southern members of Congress departed en masse in early 1861, Kansas was immediately admitted to the Union as a free state.When the admission of Minnesota proceeded unimpeded in 1858, the balance in the Senate ended; this was compounded by the subsequent admission of Oregon as a free state in 1859.