Us history the union in crisis what group of bills attempted to preserve the union despite the conflicts over slavery

Missouri compromise- it balanced the free and slave states. missouri would be admitted as a slave state and a line was drawn at the 36 30 parallel where slavery was prohibited above the line, and slavery was allowed below the line.compromise of 1850- it provided a solution to the issue regarding the newly gained territories from the mexican-american war and slavery. california would become a free state. the territories gained from the war were opened to popular sovereignty (its residents can decide whether they want to be a free or slave state). a stricter fugitive slave law was passed. the slave trade is banned in washington (not abolished).  crittenden compromise- last ditch effort to preserve the union. would reestablish and extend  the missouri compromise line. would guarantee the permanent existence of slavery in the slave states.