Final answer:
Henry Clay proposed the Missouri Compromise, which allowed Missouri to enter the Union as a slave state and Maine as a free state.
Step-by-step explanation:
The Missouri Compromise was a significant event in American history as it sought to address the growing tensions between the North and the South over the issue of slavery. At the time, the United States was expanding westward, and the question of whether new states would allow slavery or not became a major point of contention.
Henry Clay, a prominent political figure known as the "Great Compromiser," played a crucial role in brokering this agreement. Recognizing the need to maintain a delicate balance between slave and free states in Congress, Clay proposed a compromise that would allow Missouri to enter the Union as a slave state and Maine as a free state.
This compromise was significant because it temporarily eased tensions between the North and the South and helped to maintain the delicate political equilibrium. However, it also established a precedent for future compromises and negotiations over the expansion of slavery.
The inclusion of the Thomas Proviso in the Missouri Compromise was another important aspect. This provision, named after Jesse Thomas of Illinois, prohibited slavery in any new states formed north of the southern boundary of Missouri. This was a significant victory for anti-slavery advocates as it limited the spread of slavery into new territories.