Answer:
The Missouri Compromise impacted the expansion of slavery into the U.S. territories by limiting their expansion to certain areas and by setting a balance between the number of free states and slave states.
Step-by-step explanation:
When Missouri applied for admission to the Union as a slave state in 1819, the United States had 22 states: 11 were free and 11 were slaves. If the government accepted Missouri as a slave state, the balance would be shifted and the government's decision would let Americans know that it supported the expansion of slavery.
After longs debates in Congress, the issue was solved with the Missouri Compromise (1820). The Compromise stated that for every slave state, there must be one free state, it excluded slavery from the Louisiana Purchase lands north of latitude 36°30′ (except for Missouri) and it admitted Missouri as a slave state and Maine, which was originally part of Massachusetts, as a free state.