Final answer:
The Missouri Compromise was an agreement in 1820 allowing Missouri into the Union as a slave state and Maine as a free state, while banning slavery north of Missouri's southern boundary.
Step-by-step explanation:
The Missouri Compromise represented a pivotal moment in U.S. history, addressing the contentious issue of slavery's expansion into new states and territories.
In 1820, under the leadership of Henry Clay, Congress reached an agreement allowing Missouri to enter the Union as a slave state, while Maine was admitted as a free state. Known also as the Compromise of 1820, this deal maintained the Senate's balance of power between slave and free states.
To alleviate northern concerns regarding slavery's spread, the compromise also enforced the Thomas Proviso, prohibiting slavery in territories north of the 36°30′ latitude, which was Missouri's southern boundary, within the lands acquired through the Louisiana Purchase.
Though the Compromise did not solve the issue of slavery in the United States, it did manage to prevent immediate disunion by establishing a temporary sectional consensus.
The Constitution was interpreted as protecting slavery where it already existed, with the exception of the new territories delineated by the 36°30′ line, north of which slavery was banned.
This agreement incited more heated discussions on the nature of slavery and its future in America, reaffirming opposing viewpoints and accentuating the divide between the North and South.
While this decision was seen as a concession by both sides to avoid a larger crisis, it only postponed the inevitable conflict that came to a head in the Civil War.
The Missouri Compromise's legacy is complex, as it temporarily quieted the immediate tensions, but also set the stage for future conflicts over the institution of slavery.