The Missouri Compromise attempted to limit the boundaries of slavery and was later declared unconstitutional, contributing to the American Civil War. It established the line of 36°30' parallel north as the northern boundary of slavery's expansion, allowing Missouri to join the Union as a slave state while admitting Maine as a free state. While the compromise eased tensions temporarily, it increased the division between northern and southern beliefs and set a precedent for settling disputes over slavery that was later challenged. Henry Clay helped negotiate the compromise as a representative from the border state of Kentucky, using his ability to relate to both northern and southern perspectives to forge an agreement without regional bias.