The Missouri Compromise determine the balance of free and slave states, in addition to the admission of 2 new states. Passed by the 16th United States Congress on May 8, 1820, Missouri was admitted as a slave state, with Maine as a free state. This way, exactly half of the states were considered slave states, and the other half were considered the free states. This worked to diffuse sectional and political conflicts that would arise with unbalance.