What part of enumerated powers do you not understand? The XIII Amendment makes your question absurd.
Amendment XIII
Section 1
Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.
Section 2
Congress shall have power to enforce this article by appropriate legislation.
Some of our Leftist friends received all of their instruction via 'Schoolhouse Rock.'
Constitutions can be amended if enough people agree, making them pretty much useless in protecting equal rights. Just look at gay marriage, some states want it put in their constitution making it illegal. So equal rights aren't really protected in the US, unless of course the Supremes say so. Which they will. No doubt.
Thirty one is more than some.
Thirty-one U.S. state constitutional amendments banning legal recognition of same-sex unions have been adopted. Of these, ten make only same-sex marriage unconstitutional, seventeen make both same-sex marriage and civil unions unconstitutional, two make same-sex marriage, civil unions, and other contracts unconstitutional, and one is unique. Hawaii's amendment is unique in that it does not make same-sex marriage unconstitutional; rather, it allows the state to limit marriage to opposite-sex couples.
I can't find a single state that wants to pass an amendment legalizing slavery.