50 years ago there were laws on the books in certain states that declared persons of color to have fewer rights than Caucasians. I imagine the majority of those voting at that time in those states would have been perfectly comfortable to have stepped up to the ballot box to make sure the law stayed just the way they liked it because after all 'it was separate but equal'.
Just because they can vote on it doesn't make it right. Sometimes the majority is wrong. This is one of those times just as it was then.