A legal measure of the U.S. Congress designed to maintain the equal parity of free state and slave state representation in the U.S. Senate. The measure allowed Maine to join the Union as a free state while Missouri came in as a slave state. This compromise further provided that no slave state would be allowed into the Union north of 36°, 30° of latitude, nor any free state below that line. The Missouri Compromise was done in by the Compromise of 1850 which allowed California into the Union as a free state even though part of California lies south of the compromise line, and by the Supreme Court's Dred Scott decision.