MAP ACTIVITYMap 10.4 The Missouri Compromise, 1820 After a difficult battle in Congress, Missouri entered the Union in 1821 as part of a package of compromises. Maine was admitted as a free state to balance slavery in Missouri, and a line drawn at latitude 36°30′ put most of the rest of the Louisiana Territory off-limits to slavery in the future. READING THE MAP: How many free and how many slave states were there prior to the Missouri Compromise? What did the admission of Missouri as a slave state threaten to do? CONNECTIONS: Who precipitated the crisis over Missouri, what did he propose, and where did the idea come from? Who proposed the Missouri Compromise, and who benefited from it?