How was the supreme court ensured that states do not deny basic rights to the people

The Supreme Court is able to take laws under Judaical Review, as another part of the Checks and Balances. That way, another barrier to defend against unjust laws encase the legislative branch passes a unconstitutional bill that they shouldn't have, and encase the the President signs said bill into law that he shouldn't of, the Supreme Court may rule it unconstitutional and repeal it. But not just the Supreme Court, all courts may use jury nullification to nullify unjust laws or laws that are wrongfully applied.

some american cities felt workers were being oppressed by business monopolies

they had more african americans than any other state.

hope this , have a good day. c;