Final answer:
The Missouri Compromise of 1820 was a significant legislative measure designed to balance the number of slave and free states with Maine entering as a free state and Missouri as a slave state. It included a provision that prohibited slavery north of Missouri's southern border, the 36°30' line, in the remainder of the Louisiana Purchase territory, except for Missouri.
Step-by-step explanation:
Missouri Compromise Overview
The Missouri Compromise, enacted in 1820, was pivotal in the history of the United States as it addressed the contentious issue of slavery's expansion. Henry Clay played a crucial role in crafting this legislation in response to Missouri's application to join the Union as a slave state, which would disrupt the balance between slave and free states. To maintain this balance, Maine was admitted as a free state, and Missouri was admitted as a slave state. Additionally, the Missouri Comp. passed in 1820 made a rule that prohibited slavery in states from the former Louisiana Purchase north of the 36°30' line, except for Missouri itself. This measure was known as the Thomas Proviso.
As part of the Compromise, the Tallmadge Amendment, which sought to make Missouri a free state and implement gradual emancipation, was narrowly defeated. Instead, the balance was preserved in the Senate, and future conflicts were potentially avoided by establishing a geographical line, at Missouri’s southern border (36°30'), to determine where slavery would be allowed within the Louisiana Purchase territories.
The Compromise was a temporary solution to the growing sectional divide over the issue of slavery, and its repercussions were felt for decades until it was ultimately superseded by other legislative measures and events leading to the American Civil War.