Why is the Missouri Compromise Important?

Important Missouri Compromise 1820

As the United States expanded westward in the early nineteenth century, the issue of slavery was once again brought to the forefront. To address this issue, northern and southern members of Congress were forced to come to a compromise to save the Union. When it came to slavery, just why is the Missouri Compromise of 1820 important and how did it affect sectional tensions?

The topic of slavery had long been contemplated since the founding of the United States. After the animated discussions on slavery in the Federalist Papers and the three-fifths compromise included in the Constitution, the issue moved to the background for a time.

In 1803 the Louisiana Purchase added a vast amount of territory to the United States. With settlers increasingly occupying these lands in the decades following, the precarious balance of free and slave state representation in Congress threatened to come crashing down.

By 1820 signs of sectional tensions between north and south were emerging during the period known as the Era of Good Feelings. The Panic of 1819 helped to exacerbate tensions along with the lack of Democratic-Republican party discipline that featured throughout Monroe’s presidency.

When Missouri appealed to Congress for statehood in 1819 the resulting debates over the expansion of slavery in Missouri and other federal territories sparked a full-blown crisis.

Several of the founding fathers still alive—including Thomas Jefferson and James Madison—predicted the crisis could tear the nation apart.

After many rounds of negotiations the Missouri Compromise of 1820 resulted in the admission of Missouri as a slave state and Maine as a free state. It also prohibited slavery in federal territory north of the 36° 30’ parallel along Missouri’s southern border.

The Missouri Compromise marked an important step on the eventual road to the Civil War.

The Missouri Compromise Background

In the years following the Louisiana Purchase, scores of settlers moved west to populate the frontier lands. The territory of Missouri became a popular destination given its fertile farmland.

Between 1810 and 1820 the population in Missouri skyrocketed, increasing from 20,845 to 66,586. A majority of the settlers were slaveholders from the south that brought their slaves with them to the territory.1

Citizens of the territory began petitioning for statehood as early as 1817, though by 1819 the population was nearing the threshold to qualify for statehood.

The proposed state boundary’s southern border would run along the 36° 30’ parallel. Interestingly this would leave an ungoverned territory (later named Arkansas) between Missouri and the state of Louisiana.1

Missouri Compromise 1820 map
Map of the United States following the Missouri Compromise in 1820 via LOC

While the entry of Missouri into the Union as a slave state should have been routine, there was reason to believe a crisis was looming.

Northern states grew increasingly wary at the perceived unfettered spread of slavery. Even in supposed northern “free” states slavery and its practices had gained a foothold.

The Northwest Ordinance of 1787 banned slavery in the then-northwest territories of the United States, including what would become Ohio, Indiana, and Illinois. However, these states did allow indentured servitude.

Many slaveholders took advantage of this stipulation to bring their slaves to the “free” states by calling them “indentured” servants, though they would be held indefinitely.2

The paranoia over the institution of slavery was not limited to the north. Southerners knew that the north disliked the advantages slavery gave southern states in Congress. The Hartford Convention of 1814 made it apparent that northerners despised the three-fifths compromise that aided southern representation in Congress.

The tensions over slavery were soon brought out into the open in early 1819 when the House of Representatives opened debate for the admission of Missouri as a state.

The Tallmadge Amendment

The admission of Missouri to the Union turned into a national crisis with the introduction of the Tallmadge Amendment in February 1819. The Tallmadge Amendment was introduced and named after New York Representative James Tallmadge and championed by fellow New York Representative John Taylor.

Tallmadge proposed an amendment that prohibited the future introduction of slaves into Missouri and allowed for gradual emancipation of existing slaves as a condition of statehood.

James Tallmadge portrait Tallmadge Amendment
NY Representative James Tallmadge via Wikimedia

The Tallmadge Amendment effectively would make Missouri a free state instead of a slave state and was modeled on the gradual emancipation laws that the state of New York passed in 1799 and 1817.1

The attempt to limit slavery in Missouri shocked Congress and the nation. Some of the most influential figures of the time foresaw the divisiveness of the proposal and what was to come.

Thomas Jefferson famously wrote upon hearing of the Amendment:

“This momentous question, like a fire bell in the night awakened and filled me with terror. I considered it at once the knell of the Union.”1

Future president John Quincy Adams was busy negotiating the 1819 Adams-Onis Treaty yet followed along from afar and wrote that the attempt to limit slavery in Missouri was a “title page to a great tragic volume.”1

In addition to divisiveness, leading Jeffersonian Democrats at the time including Jefferson, James Madison, and President James Monroe believed the Tallmadge Amendment was not an issue of the morality of slavery, but one last power attempt by the now-defunct Federalists in the northeast.3

This opinion ignores the scores of debates ongoing throughout the north over the morality of slavery at the time.

In fact, in 1819 the Boston Yankee reflected the northern attitude by writing, “We address those who call themselves Christians… All things whatsoever ye would that men should do to you, do even so to them.”3

The Tallmadge Amendment passed in the northern-dominated House, though it was promptly rejected in the evenly-split Senate before Congress adjourned for the season.

What was the Missouri Compromise of 1820?

The Missouri Compromise of 1820 was the resolution between northern and southern members of Congress over the Missouri crisis. The compromise admitted both Missouri into the Union as a slave state and Maine as a free state to maintain the balance between slave and free states.

Importantly, the Missouri Compromise also banned slavery in federal territory north of the 36° 30’ parallel along Missouri’s southern border. The motion to ban slavery south of Missouri in the newly-formed Arkansas territory was soundly defeated in Congress.1

The 1820 Missouri Compromise background important charts

Former President Madison notably saw the Missouri Compromise as “a lesser evil” compared to the northern attempt to ban slavery in Missouri as well.4

The fact that northerners and southerners eventually compromised tends to downplay just how tumultuous and incendiary the crisis truly was.

Some members of Congress openly discussed the prospect of civil war. All indications point to representatives from Virginia as being the most uncompromising and in support of fighting over the issue.4

A key unresolved issue was whether Congress even had the authority to impose restrictions on new states. The Constitution was unclear and ambiguous, as the founders did not anticipate such future issues.

Article IV, section 3 states that “New States may be admitted by Congress into the Union.” The key word was may: northerners argued this allowed them to impose restrictions on new states; southerners did not extend that interpretation.2

Former Chief Justice of the Supreme Court and coauthor of the Federalist Papers, John Jay, issued a public letter stating support of Congress’ right to restrict slavery.2

The letter carried enormous weight and most southerners, including notable pro-slavery firebrands like John C. Calhoun, ultimately agreed that Congress did indeed have the power to restrict slavery in territories.1

Why is the Missouri Compromise Important?

The Missouri Compromise of 1820 is extremely important as it helped to stave off an immediate civil war between the north and south. Though it ultimately just postponed the eventual Civil War until 1861, the Missouri Compromise helped to guide the United States on the question of slavery through the next three decades.

Henry Clay portrait Missouri Compromise
The “Great Negotiator” Henry Clay was essential in crafting the Missouri Compromise via LOC

The compromise resulted in an uneasy truce between the north and south for at least two decades. Democratic party leaders such as Martin Van Buren took thorough steps to develop a party system that silenced discussion on slavery and helped to avoid sectional conflict over the issue.5

In the aftermath of the compromise, southern Congressmen pivoted and focused their efforts on states’ rights and battling the threats against slavery. Southern paranoia only increased in the aftermath of slave rebellions such as those led by Denmark Vesey in 1822 and Nat Turner in 1831.

The important Wilmot Proviso in 1846 would have overturned the Missouri Compromise, though it was not attached to the eventual Treaty of Guadalupe Hidalgo.

The Texas Revolution and later annexation of Texas and Mexican Cession thrust slavery back into the spotlight.

By the 1850s the Kansas-Nebraska Act of 1854 effectively overruled the Missouri Compromise by allowing the citizens of the territories of Kansas and Nebraska (north of Missouri) to choose whether or not they wanted slavery permitted.

The concept of popular sovereignty in the territories was a big topic of debate during the Lincoln-Douglas debates of 1858.

Finally, the Dred Scott Supreme Court decision in 1857 declared the Missouri Compromise unconstitutional as it declared Congress did not have the power to ban slavery in federal territories.

Though the Missouri Compromise did not last, this does not diminish the extremely important role it played in holding the Union together for a few more decades.


To learn more about US history, check out this timeline of the history of the United States.


1) Johnson, William R. “Prelude to the Missouri Compromise: A New York Congressman’s Effort to Exclude Slavery from Arkansas Territory.” The Arkansas Historical Quarterly, vol. 24, no. 1, Arkansas Historical Association, 1965, pp. 47–66, https://doi.org/10.2307/40023964.

2) Wiecek, William M. “Missouri Statehood: The Second Crisis of the Union.” The Sources of Anti-Slavery Constitutionalism in America, 1760-1848, Cornell University Press, 1977, pp. 106–25, http://www.jstor.org/stable/10.7591/j.ctt207g6m0.10.

3) Zeitz, Joshua Michael. “The Missouri Compromise Reconsidered: Antislavery Rhetoric and the Emergence of the Free Labor Synthesis.” Journal of the Early Republic, vol. 20, no. 3, [University of Pennsylvania Press, Society for Historians of the Early American Republic], 2000, pp. 447–85, https://doi.org/10.2307/3125065.

4) “Missouri Compromise.” The William and Mary Quarterly, vol. 10, no. 1, Omohundro Institute of Early American History and Culture, 1901, pp. 5–24, https://doi.org/10.2307/1919798.

5) Latner, Richard. Louisiana History: The Journal of the Louisiana Historical Association, vol. 50, no. 2, Louisiana Historical Association, 2009, pp. 213–15, http://www.jstor.org/stable/25478646.

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