Missouri Compromise: A failed attempt in 1820 to maintain a balance of power between free and slave states by admitting Missouri as a slave state and Maine as a free state while also establishing a line (36°30') where slavery would be prohibited north of it.
Compromise of 1850: An unsuccessful attempt to address issues surrounding slavery by allowing California's admission as a free state while strengthening the Fugitive Slave Act, which required the return of escaped slaves.
Kansas-Nebraska Act: A divisive law passed in 1854 that allowed residents of Kansas and Nebraska territories to decide for themselves whether they wanted slavery, leading to violent clashes known as 'Bleeding Kansas' and further heightening tensions.