if the compromise is what i think it is, the Missouri compromise was a compromise between the anti slavery and pro slavery groups to decide what states slavery would be legal in. and according to the compromise Missouri was to bee a free state, but with the condition that any territory south of it's southern border extended further into the middle of the U.S., would be pro slavery. this affected slavery's westward expansion because slaves could be taken to new plantations legally as long as they were south of the southern border of Missouri, slavery was able to expand slightly westward thereby pleasing the pro slavery groups, but also appeasing the antislavery groups because slavery was illegal in Missouri. i am pretty sure that is the answer, but it has been a while since i took a U.S. history class. hope this helps.
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Since missouri was west of the mississippi, it was one of the first "western" territories to become a slave state.
if the compromise is what i think it is, the Missouri compromise was a compromise between the anti slavery and pro slavery groups to decide what states slavery would be legal in. and according to the compromise Missouri was to bee a free state, but with the condition that any territory south of it's southern border extended further into the middle of the U.S., would be pro slavery. this affected slavery's westward expansion because slaves could be taken to new plantations legally as long as they were south of the southern border of Missouri, slavery was able to expand slightly westward thereby pleasing the pro slavery groups, but also appeasing the antislavery groups because slavery was illegal in Missouri. i am pretty sure that is the answer, but it has been a while since i took a U.S. history class. hope this helps.