The Missouri Compromise of 1820 was historically significant as it attempted to balance the power between slave and free states in the U.S. Congress. It emerged in response to the contentious debate over whether Missouri would enter the Union as a slave state. The compromise allowed Missouri to join as a slave state while Maine entered as a free state, maintaining the political balance. It also established the 36°30′ parallel as the line demarcating future free and slave territories in the Louisiana Purchase. This temporary solution highlighted the growing sectional tensions over slavery, foreshadowing further conflicts leading to the Civil War.