The right answer is Maine would be a free state, and Missouri would be a slave state.
The onset of a fierce sectional controversy over efforts to expand slavery into the new western territories. The Senate decided to link Maine’s request for separate statehood with Missouri’s and voted to admit Maine as a free state and Missouri as a slave state, thus maintaining the balance between free and slave states in the Senate. A senator from Illinois, Jesse Thomas, further extended the so-called Missouri Compromise by an amendment to exclude slavery from the rest of the Louisiana Purchase north of 36°30′, Missouri’s southern border.