This question has recently re-surfaced in the context of Democratic candidates' for 2020's evident desire to make serious changes to the US Constitution with regard to the electoral college, the supreme court and similar matters.
The US Constitution can legally be changed in two ways:
-By amendment. We have done that throughout our history, choosing to change the document paragraph by paragraph after a deliberately difficult process of Congressional approval and state ratification. (2/3 of each house of Congress agreeing and 3/4 of the states ratifying) Many, many amendments proceed only part way through the process and then fail, never becoming part of the constitution. Think of the Equal Rights Amendment (ERA). Has it been 45 years that it has waited for state ratification?
-By Constitutional Convention, like the first time in 1789. This will not happen. Why? The states would be free to ratify or not ratify the new document and those that did not would be out of the Union. (If that is not true, tell me why.) Who will risk that? Who will risk the possibility that the Red/Blue divide in this country is not so serious that it would produce such a result. Already there is much talk of polarization to the point of alienation. What would be the result if Red Staters could rid themselves of Blue Staters or vice versa without an overt penalty.
IMO, if a constitutional convention were convened it would effectively become the supreme law of the land. That is what happened with the convention that created the USA as we know it. The convention in Philadelphia was convened to "adjust" the Articles of Confederation. Once convened, the delegates seized control and created a completely new system of government. The states are the contracting parties to the constitution and so the new constitution had to be submitted to the states for ratification. Two states, Rhode Island and North Carolina voted to reject the new government before Virginia, by the slimmest of margins, voted yes to "close" the deal. It took several years and the Federalist Papers to obtain that final ratification. RI and NC then changed their minds rather than be left isolated with the Europeans still on their "doorsteps."
Would not the large states wish to end the "great compromise" that gives each state (however small) two seats in the senate? To do that would require the acquiescence of the small states in a process of ratification. Would Wyoming or Vermont or any of the other "small" states do that for California or Florida? If frustrated in this process would Texas or any of the other big states leave the new country by rejecting ratification?
How many other provisions of the present constitution would be challenged? Name a few. How about the Income Tax Amendment? How about popular election of US Senators?
Spare me any cant about "economic viability." All over the world we have examples of states which are anything but economically viable but which exist because people there just couldn't "stand" being bound to some other group of people within the loving embrace of a constitution. In any event, trade is not limited to national territory.
The accepted wisdom in the USA has been that regional cultural differences are disappearing under the influence of migration and the universal prevalence of a "national" (read Northern) culture. It is mostly Northerners who say this. They have been saying it since the 1830s. Places like Atlanta and northern Virginia seem to support this view, but if you ask you will find that most of the proponents of that view who live in the metropolitan areas rarely leave those areas except by air or rail. They don't feel "comfortable" wandering around the countryside. Why is that?
The contrarian view is that, in fact, the regions and their cultures are actually growing farther apart, and that the values of places like New York City and the Piedmont region of the Upper South are farther apart than ever before. This time it is not just a question of the culture of the South being "different." Look at the Red/Blue Map by counties all over the country for the last two elections. Look at places like California and Oregon. Look at New York State. The rural areas are Red if the population there is not a minority or solidly "labor" like the Masabi Iron Range in the far north, while the cities are Blue just about everywhere. These divisions are deepening, not disappearing. It would seem that now the split is rural/urban, as well as regional.
Let's not have another constitutional convention, not ever. We are not Canada. The Canadian government said years ago that a Quebec decision for "sovereignty" would be accepted. I can't imagine that happening here and I would fear the result if it were attempted. pl