The Missouri Compromise of 1820 prohibited slavery in the territory north of the 36°30' parallel, except for Missouri. This was a significant agreement as it helped to balance the number of free and slave states in the US at the time.
The Compromise of 1850 allowed California to enter the Union as a free state and abolished the slave trade in Washington D.C. It also introduced the Fugitive Slave Act, which required citizens to assist in the capture of runaway slaves.
The Kansas-Nebraska Act of 1854 repealed the Missouri Compromise and allowed the residents of the territories of Kansas and Nebraska to decide for themselves if they wanted to allow slavery or not. This decision, known as popular sovereignty, resulted in a violent conflict between pro-slavery and anti-slavery forces in Kansas, known as "Bleeding Kansas."
Overall, the Missouri Compromise and Compromise of 1850 attempted to balance the number of free and slave states, while the Kansas-Nebraska Act allowed for the expansion of slavery into new territories.