When Missouri applied to become a state in 1820, there were currently _______ free states and 11 _______ states. The addition of Missouri into the Union would have upset the _______ of free states and slave states, so Henry Clay proposed a compromise which allowed Missouri to join as a _______ state if Maine joined as a free state, thereby keeping the balance between Northern and _______ state representation equal in the _______ . This agreement is known by historians as the Missouri Compromise that established the 36°30' line, which determined that all states _______ the line would become free states - except for _______ - while all states below the line would become slave states.