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Issued on March 3,1820.
The Missouri Compromise was an effort by the U.S. Senate and House of Representatives to maintain a balance of power between the slave holding states and free states. The slave holding states feared that if they became outnumbered in Congressional representation that they would lack the power to protect their interests in property and trade.

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Issued on January 1,1831.
The liberator (1831–1865) was a weekly abolitionist newspaper, printed and published in Boston by William Lloyd Garrison and, through 1839, by Issac Knapp. Religious rather than political, it appealed to the moral conscience of its readers, urging them to demand immediate freeing of the slaves, it also promoted women's rights, an issue that split the American abolitionist movement.

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Issued on August 21,1831.
Nathanial “Nat” Turner was an enslaved man who led a rebellion of enslaved people. His action set off a massacre of up to 200 black people and a new wave of oppressive legislation prohibiting the education, movement, and assembly of enslaved people. The rebellion also stiffened proslavery, anti-abolitionist convictions that persisted in that region until the American Civil War (1861–65).

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issued on April 25,1846.
The Mexican-American War (1846-1848) marked the first U.S. armed conflict chiefly fought on foreign soil. It pitted a politically divided and militarily unprepared Mexico against the expansionist-minded administration of U.S. President James K. Polk, who believed the United States had a “manifest destiny” to spread across the continent to the Pacific Ocean. A border skirmish along the Rio Grande started off the fighting and was followed by a series of U.S. victories. When the dust cleared, Mexico had lost about one-third of its territory, including nearly all of present-day California, Utah, Nevada, Arizona and New Mexico.

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issued on January 29,1850.
The Compromise of 1850 consists of five laws passed in September of 1850 that dealt with the issue of slavery and territorial expansion.It admitted California as a free state, left Utah and New Mexico to decide for themselves whether to be a slave state or a free state, defined a new Texas-New Mexico boundary, and made it easier for slaveowners to recover runways under the Fugitive Slave Act of 1850.

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Issued on March 20, 1852.
Uncle Tom's Cabin; or, Life Among the Lowly is an anti-slavery novel by American author Harriet Beecher Stowe. Published in 1852, the novel had a profound effect on attitudes toward African Americans and slavery in the U.S. and is said to have "helped lay the groundwork for the Civil war".

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Issued on March 20,1854.
The Republican Party was founded in the Northern states in 1854 by forces opposed to the expansion of slavery, ex-Whigs, and ex-Free Soilers. The Republican Party quickly became the principal opposition to the dominant Democratic Party and the briefly popular Know Nothing Party. The party grew out of opposition to the Kansas-Nebraska Act, which repealed the Missouri Compromise and opened Kansas Territory and Nebraska Territory to slavery and future admission as slave states. The Republicans called for economic and social modernization. They denounced the expansion of slavery as a great evil, but did not call for ending it in the Southern states.

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Issued on May 30,1854.
The Kansas-Nebraska Act was a bill that mandated “popular sovereignty”–allowing settlers of a territory to decide whether slavery would be allowed within a new state’s borders. Proposed by Stephen A. Douglas–Abraham Lincoln’s opponent in the influential Lincoln-Douglas debates–the bill overturned the Missouri Compromise’s use of latitude as the boundary between slave and free territory. The conflicts that arose between pro-slavery and anti-slavery settlers in the aftermath of the act’s passage led to the period of violence known as Bleeding Kansas, and helped pave the way for the American Civil War (1861-65).

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Issued on May 22,1856.
The Caning of Charles Sumner, or the Brooks–Sumner Affair, occurred in the United States Senate, when Representative Preston Brooks, a pro-slavery Democrat from South Carolina, used a walking cane to attack Senator Charles Sumner, an abolitionist Republican from Massachusetts, in retaliation for a speech given by Sumner two days earlier in which he fiercely criticized slaveholders, including a relative of Brooks. The beating nearly killed Sumner and it contributed significantly to the country's polarization over the issue of slavery. It has been considered symbolic of the "breakdown of reasoned discourse" and the use of violence that eventually led to the Civil War.

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Issued on March 6,1857.
The Dred Scott case, also known as Dred Scott v. Sandford, was a decade-long fight for freedom by a Black enslaved man named Dred Scott. The case persisted through several courts and ultimately reached the U.S. Supreme Court, whose decision incensed abolitionist, gave momentum to the anti-slavery movement and served as a stepping stone to the Civil War.

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Issued on October 18,1859.
The raid on Harpers Ferry was intended to be the first stage in an elaborate plan to establish an independent stronghold of freed slaves in the mountains of Maryland and Virginia—an enterprise that had won moral and financial support from several prominent Bostonians. Choosing Harpers Ferry because of its arsenal and because of its location as a convenient gateway to the South, John Brown and his band of 16 whites and five blacks seized the armoury on the night of October 16. Sporadic fighting took place around the arsenal for two days. On October 18, combined state and federal troops (the latter commanded by Col. Robert E. Lee and including Lieut. Jeb Stuart subdued Brown and his collaborators. Seventeen men died in the fighting.

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Issued on November 6,1860.
Abraham Lincoln is elected the 16th president of the United States over a deeply divided Democratic Party, becoming the first Republican to win the presidency. Lincoln received only 40 percent of the popular vote but handily defeated the three other candidates: Southern Democrat John C Breckinridge, Constitutional Union candidate John Bell, and Northern Democrat Stephen Douglas, a U.S. senator for Illinois.

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Issued on December 20,1860.
South Carolina became the first slave state in the south to declare that it had seceded from the United States. James Buchanan, the United States president, declared the ordinance illegal but did not act to stop it.