Final answer:
The Missouri Compromise of 1820 divided states into slave and free states, maintaining a balance in the Senate. It established a dividing line between slavery and freedom in the unorganized territory of the Louisiana Purchase. The compromise revealed the divisive nature of the slavery issue and reignited debates over the Constitution and slavery's morality.
Step-by-step explanation:
The Missouri Compromise marked a major turning point in America's sectional crisis because it exposed to the public just how divisive the slavery issue had grown. The compromise was reached in 1820 and brought Missouri in as a slave state and Maine in as a free state, maintaining a balance in the Senate.
The Missouri Compromise also established a dividing line, known as the 36°30′ line, between slavery and freedom in the remaining unorganized territory of the Louisiana Purchase. Slavery could expand south of this line, but not north of it.
The compromise, led by Speaker of the House Henry Clay, showcased the deep division between anti-slavery and pro-slavery forces in America, and reignited debates over the Constitution and the morality of slavery.