Before the civil war, the south’s economy was based on enslaved labor. large cities. immigrant workers. factories.

the answer is

answer: in october 1962, an american u-2 spy plane secretly photographed nuclear missile sites being built by the soviet union on the island of cuba. president kennedy did not want the soviet union and cuba to know that he had discovered the missiles. he met in secret with his advisors for several days to discuss the problem.

explanation:

missouri compromise of 1820 which prohibited slavery