The reason that the 15th amendment, passed in 1870, was partially unsuccessful was: a. mostly southern states failed to enforce it c. part of it was found to be unconstitutional b. mostly northern states failed to enforce it d. many states did not understand it

How did the invention of the cotton gin affect slave labor in the united states? a. there was a forced migration of slaves from the south to the north. b. slave-owning cotton planters were gradually forced to sell their plantations. c. more slaves were purchased to work on cotton plantations in the south. d. the reduced need for labor on cotton plantations led to a decline in slavery. e. slaves were moved from cotton plantations to sugar plantations.