slaves were not considered citizens, they had no rights at all, 13th freed them ,the 14th amendment, ...which was originaly intended only for slaves, stated if they were born here or naturalized here, they are u.s. citizens and citizens of the state they are in.
since they are considered free citizens, all rights now apply to them....no amendment to the constitution can grant a right, only the court can recognize a right, and that is what they did, the amendments to the constitution, state that the right to vote cannot be denied, because of race, sex.
no where in the constitution do you see a granting or giving of rights...government can give a privilege...but not a right.
the constitution grants powers to the federal government, it does not grant rights to people, it recognizes rights.......the bill of rights are not rights.......they are restrictions on government.