The Missouri Compromise added Maine and Missouri as new states, and specified a dividing line between slave and free states.
The Missouri Compromise (1820) admitted Missouri into the Union as a slave state with Maine being added at the same time as a free state, to keep the balance of slave and free states equal. The Missouri Compromise also prohibited any future slave states north of the latitude line 36 1/2 degrees north of the equator in territories of the Louisiana Purchase, with the exception of Missouri (north of that line) being admitted as a slave state.
