Arguably the United States was formed as a perpetual union under the Articles of Confederation, and its government was reorganized under the Constitution leaving the perpetual union part intact. The Constitution references the Union as an existing entity. If I recall correctly Madison joined Hamilton in writing Federalist 18. 19 and 20 under the title "The Insufficiency of the Present Confederation to Preserve the Union."
The “Letter of the President of the Federal Convention, Dated September 17, 1787, to the President of Congress, Transmitting the Constitution” states:
The friends of our country have long seen and desired, that the power of making war, peace, and treaties, that of levying money and regulating commerce, and the correspondent executive and judicial authorities should be fully and effectually vested in the general government of the Union: But the impropriety of delegating such extensive trust to one body of men is evident-Hence results the necessity of a different organization.
This letter notes the necessity of a different organization of the government of the Union and was sent to the representatives of the States that composed the Union. (The Federal Government is not the United States. It is a governing mechanism or agent agreed to by the States.) There is no indication that the Union was intended to end, just a change in the governing mechanism for it.
Looks to me like it flows.
Note that I have not maintained that a state has no right to secede. What I maintain is that the other states may have a right to object to that secession. Some of the States tried to "bust the deal" and were forced to "face the wheel." In this case, the "Wheel" was a form of Judicial Combat. Arguably, Lincoln and the Federal Government acted on behalf of the States which did not agree with the decision of other States to back out of a deal they had agreed to (before the Constitution existed).
Regarding the Louisiana Territory, if one of the States formed from that Territory decided to secede, and the remainder of the States agreed to the Secession, should those remaining States demand that the State vacate the land in question, or pay for it? After all, the United States paid $15 million in good American dollars for that land and there is no reason to allow somebody to abscond with it without payment, like they had conquered it in war or something.
Or maybe not. Do you have an opinion on the Constitutional basis for the purchase of the Louisiana Territory? Maybe none of them are legally part of the United States anyway.
I suppose it is arguable, but seeing as the Articles of Confederate use the term both times in reference to those same articles, a more plausible explanation suggest that the term applied only as far as the articles themselves remained intact. The first is in the document's reference to itself as "articles of confederation and perpetual union," and the second states that the union "shall be perpetual" under what it describes as the "articles of this confederation." Thus each description of the union in that document comes as an attribute to the articles themselves. It seems to follow that, if those same articles cease to be the governing mechanism and are replaced by something else, the attributes they give to themself also share in the fate of the articles.
The Constitution references the Union as an existing entity.
That it does, but a common mistake of many is to take a simple reference to "the Union" or a statement praising the benefits of "the Union" as if it were an endorsement for perpetual and inescapable membership in that same union. The Constitution makes no statement asserting the perpetual nature of "the Union," though it does use the term union. It would be fallacy though to conclude that the former is true by virtue of the latter's presence alone.
If I recall correctly Madison joined Hamilton in writing Federalist 18. 19 and 20 under the title "The Insufficiency of the Present Confederation to Preserve the Union."
Even so, simple praise of the union or a call to preserve it intact is not the same as a mandate perpetually binding its membership to that same union. It is a similar fallacy to identify simple advocacy of the union itself then conclude, based upon it alone, that the union's nature is inseparable.
This letter notes the necessity of a different organization of the government of the Union and was sent to the representatives of the States that composed the Union.
That it does, but again, a simple reference to the concept of the union, the functions of that union, or the benefits of that union does not constitute an assertion of that union's permanency. It is fallacy to insert that final step where there is none.
Note that I have not maintained that a state has no right to secede. What I maintain is that the other states may have a right to object to that secession.
The right to assert an objection is itself an obvious right of the other states. The issue is the degree in which they may assert this objection - specifically, does it mean they may simply urge their colleagues against secession, may they require that qualifications be met in order to secede, may they require their own full consent for secession to occur, or may they exert coercive force against a seceding state to prevent it from exercising an act of secession against their consent? Alexis de Tocqueville addressed this issue by noting that, ultimately, little could be legitimately done to stop secession. An act of coercion itself against a seceding state by an objecting state would itself be a violation of the Constitution's founding principle, thus making it the greater illegitimacy. As Tocqueville put it:
"If it be supposed that among the states that are united by the federal tie there are some which exclusively enjoy the principal advantages of union, or whose prosperity entirely depends on the duration of that union, it is unquestionable that they will always be ready to support the central government in enforcing the obedience of the others. But the government would then be exerting a force not derived from itself, but from a principle contrary to its nature. States form confederations in order to derive equal advantages from their union; and in the case just alluded to, the Federal government would derive its power from the unequal distribution of those benefits among the states."
Regarding the Louisiana Territory, if one of the States formed from that Territory decided to secede, and the remainder of the States agreed to the Secession, should those remaining States demand that the State vacate the land in question, or pay for it? After all, the United States paid $15 million in good American dollars for that land and there is no reason to allow somebody to abscond with it without payment, like they had conquered it in war or something.
In such a case, the question becomes one of a right to make such a claim. Upon the settlement of those lands, ownership of the inhabited properties will generally belong to those who inhabit them or use them to whatever purpose is theirs. Accordingly, to ask that they vacate that land or pay another state that has no singular or direct claim of ownership to it for that land's use is akin to robbery. In theory, this issue could extend as well to federal properties within a seceding state. Suppose that Louisiana, for example, desires to secede. It is true that the people of Louisiana havte paid taxes to the federal government just like those of Massachusetts or any other state, and those taxes are presumably used to build things - let's say forts - in both Louisiana and Massachusetts. If Louisiana decides to leave the union, should Massachusetts have any more claim to a fort within the boundaries of Louisiana than Louisiana does? Just the same, should Louisiana have any more claim to a fort within the boundaries of Massachusetts? If Louisiana were to secede it would no doubt be asserted by some in Massachusetts that they were "stealing" a fort paid for by Massachusetts tax dollars, but such a claim would be disingenuous as Louisiana tax dollars also paid for that same fort and for other forts outside of Louisiana. One could, I suppose, attempt to determine values and ownership based on formulas of federal tax contributions by state, but doing so would be a logistical, mathematical, and political nightmare. Instead it seems that the most prudent method of determination is geographical.
Do you have an opinion on the Constitutional basis for the purchase of the Louisiana Territory? Maybe none of them are legally part of the United States anyway.
Very possible. It would probably come down to whether or not the territory's de facto acceptance and admission into the United States supersedes the constitutionally sketchy ground on which it was obtained.