So in this timeline, the Monroe Doctrine will be more like an America-only continent-wide NATO led by the big three (US, Argentina, Mexico) and less a US extortion racket?
I can see the US being denied Mexico's territory...and then decides to conquerliberate Canada from the British and getting massively supported in this endeavor by Mexico and Argentina (because fuck Old World Colonizers, right?). So the ITL US basically controls everything north the Rio Bravo as per Adams-Onís treaty, including Canada and Alaska.
The Monroe Doctrine might be considered a theoretical American guarantee of independence for the new Latin American countries, but in practice their response is going to be "thanks" and shrug: the UK was more important in the early years of the doctrine, and all of the new countries are on very favorable terms with the UK. This also makes Latin American support for a US war against British Canada vanishingly unlikely: it would be a distant war by an "ally" who contributed no material aid to the wars against Spain against one who contributed a great deal of it.
I daresay that conflict between Mexico and the US is all but inevitable, but it won't be quite the one-sided affair from OTL; I can't say much more than that, because even the ersatz Texan revolution is still several years away.
I THINK would not even exist all
The Monroe Doctrine exists, but it's a lot more clearly for domestic consumption than IOTL; by 1823, when the doctrine is getting more or less formalized as American foreign policy, the independence wars have been done for 2 years and the coalition of Colombia, Perú, Chile and the United Provinces managed to do it on their own, so while they appreciate it, they still consider it little more than a gesture (and in some circles, even a veiled threat).
This is certainly an interesting timeline and while I do not agree with the way you have represented some things (eg Artigas wasn't half of a nice guy as you show him to be) I've liked it so far (wank or not), nevermind that SA stories (nevermind one about Argentina) are super rare.
I've certainly painted him in a very favorable light ITTL, but it has helped in that regard that he hasn't suffered as many setbacks, hasn't been betrayed quite as spectacularly, and hasn't been at war for essentially half his life (well, not
just at war). But for example the reason that
he inaugurates the era of punitive military campaigns against natives on the border is because that was a policy he supported IOTL, and he was not alone in his generation in believing that the revolution needed to be secured by force, including against natives who refused to integrate.
I am glad that you've enjoyed it so far!
One question I have is if you have some specific plan for the development of the country or if you are just "letting history write itself", as the Federal push ITTL seems like it could end rather badly (as the numerous reforms and ever growing power of the Federal government in the US has shown us, a neutered central government is basically useless), nevermind that realistically most of them will be power hungry caudillos who unlike the other power hungry caudillos (who want a more unified nation) just want to rule their provinces as their own little fiefs.
The reason I've hinted at an imminent shift in the political landscape is that the phenomenon you mention here is going to come to the forefront during a Federalist-run national government; to use an analogy ripped from the US, I see it a bit as a High-Federalist period giving way to a Jeffersonian period, with the most conservative elements of Platine society not being too pleased with either, which comes to the fore in the 1830s as the Federalists start to fracture over the question federal authority, and as its most conservative elements start pushing back against the continuation of radical policies like land reform and some timid steps towards native integration (the Guaraní are a huge Federalist constituency ITTL for example).
I've employed a bit of a mix: I had some specific plans for how I thought the government would develop, but I've attempted to build out from there organically. So while I had a pretty clear idea of how I wanted the General Assembly to develop, the position of Supreme Director developed on the fly in my writing as much as ITTL.
The Monroe doctrine will probably exist in a similar manner as OTL. While the situation is seemingly better, the UP are still waaay far behind the US in development and power and unlike the US they are surrounded by many potential enemies. Nevermind that we don't even know of Colombia will survive long term (I mean it didn't in OTL) or that the UTP won't fracture either.
You're correct that the US has a huge lead in development and population, with the United Provinces coming in at just
barely 1/5th the population of the United States, but relations with Perú and Chile are much better than OTL, so the UP only really has Brazil to worry about. And with Brazil's independence from Portugal in 1822, the dynamic between them and the UP has shifted a bit, even if Rio Grande do Sul is... let's just say not a welcoming place for Platine citizens (and a downright deadly place for a Platine citizen who a) fought in the army or b) was once a slave).
Colombia will survive, due in no small part to avoiding the 5 bloody years of fighting in Perú and Bolivia, although it'll be, well, a lot more American, in that it's going to involve a constitutional convention in the 1825-26 period to prevent Venezuela from rising in open revolt and to keep Guayaquil in particular from getting too aggravated by their incorporation into a country whose constitution they had no say in creating.
The countries that are on the shakiest foundation ITTL are, for similar reasons to OTL, the Federal Republic of Central America and the Empire of Mexico; the Federal Republic might fare
ever so slightly better, but it'll be tough to survive the 1830s. As for Mexico, I think my indulgent decision to keep the First Empire is going to bite the country on the ass
pretty hard.
