By [the Articles of Confederation], the Union was solemnly declared to "be perpetual." And when these Articles were found to be inadequate to the exigencies of

By [the Articles of Confederation], the Union was solemnly declared to "be perpetual." And when these Articles were found to be inadequate to the exigencies of the country, the Constitution was ordained "to form a more perfect Union." It is difficult to convey the idea of indissoluble unity more clearly than by these words. What can be indissoluble if a perpetual Union, made more perfect, is not?. . . When, therefore, [a state] became one of the United States, she entered into an indissoluble relation. All the obligations of perpetual union, and all the guaranties of republican government in the Union, attached at once to the State. The act which consummated her admission into the Union was something more than a compact; it was the incorporation of a new member into the political body. And it was final. — U.S. Supreme Court, Texas v. White (1869). https://en.wikipedia.org/wiki/Perpetual_Union https://en.wikipedia.org/wiki/Perpetual_Union