Henry Clay proposed it to even out the balance of free and slave states. The states were Missouri, which entered as a slave state, and Maine, which entered as a free state.
What Two States Became States As A Result Of The Missouri Compromise Of 1820?
Missouri entered the Union as a slave state while Maine entered the Union as a free state as a result of the Missouri Compromise suggested by Henry Clay of Kentucky so there will be a balance of free and slave states.