They were not withheld from the States. Your persistently saying so stands Constitutional history on its head. Those powers belonged to the States, which otherwise would not have had any authority to delegate them to the United States of America under the Constitution.
Read the specific language of the first sentence of Articles I, II, and III: it speaks of Powers that shall be vested. But by whom? Look at Article VII (emphases mine):
"The Ratification of the Conventions of nine States, shall be sufficient for the Establishment of this Constitution between the States so ratifying the Same."
Whoop! There it IS!! It is not a self-sourcing, self-originating, self-creating document, but a created Thing, which names its creators in that sentence. The clincher is the second clause of the same Article:
"done in Convention by the Unanimous Consent of the States present the Seventeenth Day of September ....."
Quod erat demonstrandum.
I repeat: If these sovereign powers had not inured to the States from the outset, the Constitution would not have enumerated them at all, since it would have been obvious to all observers that the States did not dispose of these powers to begin with.
Your interesting rewriting of the XIII is typical and totally FUD.
I'm sorry, I don't know what you mean by that. I merely attempted to state, as part "b", in additional clauses of the XIIIth, the unwritten but nevertheless operative changes which I believe Abraham Lincoln made to the Constitution by victoriously warring on the South. The English Constitution has been occasionally modified by acts rather than writs or laws over the centuries; and without passing on their way of amendment as distinct from ours, I wanted merely to point out that Lincoln had, in fact, effectuated such unwritten amendments to our own Constitution -- such as the implosion of the Tenth Amendment under cooperative assaults by Congress and the Courts asserting the Commerce Clause power in the teeth of the Tenth.
Because of the fact that slavery existed at the start of the Union, an amendment was needed to end it, because of the 10th amendment and the fact that slavery was one of those "reserved rights" that you are so proud of. You might note that the XIII was ratified with the help of the *real* legislatures of many of the southern states - unlike the [XIVth], which was only ratified after these same legislatures were removed by the federal government.
If the ex-Confederate state legislatures met and ratified the XIIIth Amendment, that is currently news to me (I can't swear I never heard of it), and of course raises questions of compulsion (1,000,000 troops). But I can see numbers of ex-Confederate legislators taking the conciliatory view Longstreet took, even though I believe that view was in the minority in the South.