Dumb question for asking but is it possible for the Spanish colonies in the Americas to technically be administrated as a Crown of Mexico, much like how there was a Crown of Castile or Aragon? Semantics but just asking.
Ooh! Spanish Colonial History, My Forte! (Don't look at my username. Don't!) lol.
So, to answer your question, yes, but no.
A crown was seen as an ancient title, one that demanded its own privileges and rights, and oftentimes, had its own culture, history, and royalty/nobility. In Iberia, and in Europe generally, having two crowns in the same country (Through personal unions) would oftentimes lead to problems moving forward as oftentimes the weaker crown(s) would attempt to safeguard their privileges and rights come hell or high water, ending either in the weaker crown being essentially obliterated or the union ends. This was seen in English history with Scotland, Austria with Hungary, and, most importantly for our discussion, in Spain with Aragon (and Navarre and the Netherlands but don't worry about them). The issue with having a crown in America is that it wasn't necessary nor desired for Spanish control.
When Spain came to the new world, the Spanish Kings made very well damn sure that none of the noble, privilege, and autonomy problems that plagued them in Iberia would continue on in the New World. Hence, the entirety of the New World was under the direct rule of the King in Spain or his chosen subordinates in the Indies. (If I remember correctly, there were to be no noble titles granted in the Indies, and all of the LAND, PEOPLE, and RESOURCES in its ENTIRETY were technically Royal Property/under Royal Tutelage) Sure, the Indies (as the Spanish called the new world) had a council in the same way that Aragon, Portugal, or Flanders had, but the council in the Indies was directly under the command of the king and had no right to resist whatever orders he gave, whereas the ones in the old world technically didn't either but oftentimes did as a result of the political compromises their previous kings made, which the new one would have to keep, (or reform). On top of that, in the early medieval period, it was thought that royal titles were granted through the Pope and Christendom. Even if this idea was beginning to fade away into irrelevance, it would still be important enough in Iberia (Perhaps more so in this case as it was only through the Pope's blessing (Treaty of Tordesillas) that Spain even got the territory to begin with) so it might be that a particularly Pious King would only crown himself King of Mexico if he had the blessing of the Pope.
So, clearly, there are a lot of challenges to creating said crown in the New World: Mainly that if it was granted similar privileges as crowns in Europe, that would be counterproductive to Spanish desires, the creation of the titles wasn't really necessary to achieve Spanish goals in the Indies, and, most benignly, would just be an extra title to the King of Spain and not really change anything politically or economically.
But let's just ignore that because KING FELIPE WANTS HIS TITLES!
Just for the LOLS, I came up with a couple of Alt. His. Scenarios where such a thing would occur (may or may not be realistic),but hope you enjoy:
1.) Montezuma's ... Betrayal?
POD(s): The Spanish arrive a bit earlier in Mexico than OTL (Perhaps a shipwreck) and the diseases which plagued the Aztecs have even more time to fester before the Spanish conquest begins. The end result being that the Aztecs are even weaker and its society more or less collapsing by the day. When the Conquistadors (Perhaps lead by someone other than Cortez) arrive in Tenochtitlan with their Tlaxcalan allies, Montezuma is a destroyed man, his will completely broken as he is unable to save his own society and people, and submits to Spanish demands to convert to Catholicism and pledge his Fealty to the Spanish King. This naturally angers the Nobles and the Locals (Vichy France, just 400 years early) who revolt and proclaim a new leader as their Tlatoani. This gives the Alt-Cortez Causus Beli to put down the rebellion and conquer the remaining kingdom as he is merely restoring/defending an Ally and Vassal of the King of Spain. Montezuma (and his family if they follow him), meanwhile, is whisked away to Cuba and perhaps to Spain where he is kept and Europeanized as a "Guest" of the King of Spain. He is official named Prince of Mexico by Spain, although he is likely kept away from Mexico as his presence might inspire a rebellion (Although he probably wouldn't be well-liked by his former countrymen either for obvious reasons) A Native Crown of Mexico exists, albeit a hollow one with no authority over its own affairs as it is increasingly integrated to the Viceroyalty of New Spain.
2.) Pizarro's Folly
In November of 1542, the promulgation of the Leyes Nuevas de Burgos (The New Laws of Burgos, a new law code to be used in the governing of the Indies) caused mass outrage and fury among the colonists who saw their privileges and rights reduced massively. In a Revolutionary Mood, the leading colonists rallied around Gonzalo Pizarro and proclaimed him King of Peru. The Viceroy of Peru was killed, while Bartomoleo de las Casas was jeered from his estates in Santo Domingo and forced to flee. By 1545, Royal Authority not only in Peru but also in Mexico and the Indies began to collapse and many feared a new Communero Uprising, but this time in the New World. (POD) In his fright, His Majesty sought to concede to the rebels and repeal most of the harsher laws but Fernando Álvarez de Toledo, 3rd Duke of Alba (The Iron Duke) managed to convince His Majesty that the only way out of the present calamity was to teach the colonists the lesson to never again resist Royal Authority in such a manner. With the agreement of the King of Spain, an Entire Armada, along with 20 thousand men, was dispatched under the leadership of the Duke of Alba to the New World. Pizaro's Revolt, as it became to be known, was a 5-year conflict as the Iron Duke violently put down any and all attempts at resistance. Encomienda's were burned, wealth seized, and traitors executed. It was bloody and extreme but, in the end, his Majesty's forces prevailed. The Leyes Nuevas were enforced with full zeal by the Duke of Alba along with many more stipulations that defacto wiped out many of the Encomiendas and terminated the conquistador's influence over the Indies. Bureaucrats, Clergy, and Knights from the Orders of Chivalry in Spain were brought imported in order to better govern the Indies and better repair the damage done from 5 years of war and 50 years of incompetence. In order to spite the remaining conquistadores, sufficiently Hispanisized Indios were granted Estancias and were allowed even greater rights than had been allowed under the Leyes Nuevas, Fully enforced by Las Casas and the church. In one final act, The Duke of Alba (Granted complete control over the Indies for the duration of his time there) gave the King of Spain Three New Titles: The King of Mexico, The King of Peru, and the King of the Indies. Now, nobody other than the King of Spain can claim authority over the Americas. A new era in Spanish history is about to Begin.
3.) The Really Boring Option.
POD: His Majesty, Phillip V, The Bourbon King of Spain gazed out the window. Ever since the War of Spanish Succession, he needed a way to boost the prestige of Spain and of the Bourbons. He looked at a map of the Indies nearby and the shape of new, foreign land. Perhaps he could be made King of Mexico? So, Phillip V of Spain was made King of Mexico.
4.) A Last Ditch attempt.
POD: The Spanish Royalty pull a Portuguese Royalty by fleeing to the New World to escape from the French Roy- Imperials.
Recognizing that it would either be revolt or reform in his new sanctuary, Carlos IV accepts some of the demands from the Colonial Rebels: greater rights, a greater say in government, and the creation of 5 Kingdoms equal to the Kingdom of Spain: The Kingdom of New Spain, The Kingdom of New Granada, The Kingdom of Peru, and the Kingdom of Rio de la Plata. While many in the colonies celebrated the reforms, in reality, much of them were the result of court intrigue rather than anything the king personally came up with. Old and weak, Carlos hoped the reforms would stabilize the colonize just enough so that he may someday return to Spain. Little did he know, he wouldn't see his home country ever again....
Had to wrap those last two up really quickly lest I write for another three pages. Hope I go the ball rolling on this thread again.
what was the deal with all the kingdoms in New Spain (ie Kingdom of New Leon)? Logistically, they were merely administrative districts, but them being labelled as kingdoms implies there's a crown (which I presume was worn/held by whomever was the King (or Queen) of Spain, which itself had a bunch of kingdoms.
As an aside, I wrote (not all that well) a TL whereby there was a surviving brother to Louis XIV (France) who won rights to the Spanish Crown during the 9 years war. Long story short, things got mangled in the War of Spanish Succession, and that brother ended up ruling a Kingdom of Mexico. Very well, I might add, and he spawned a bunch of Kings who took over various colonies to rule as independent kingdoms.
I've long been fascinated by the idea of carving Mexico out of the Spanish colonial empire. I've never seen any hint of trying such a thing during the partition treaties looking to carve up Carlos II's empire circa 1700, so I'm guessing that was either not desired (I don't think England/Britain would like such a New World precedent being set in that era), or European royalty of the major houses would laugh heartily at the notion of going to the backwoods American continent.
A century later, Bernardo de Galvez was the hero of the American Revolution for recapturing Florida (or parts of it), and was a popular vice regent of New Spain when he died suddenly. There were suspicions that he was poisoned by the Crown over fears that Bernardo might think about making himself leader of an independent Mexico. I've thought that might be a good POD: King Bernardo
@unprincipled peter Technically, they weren't actual kingdoms since it was just a name. The Administrative division's name was Nuevo Reyno de León literally translating as the New Kingdom of Leon. (Think of it like Colonial Mad-Libs, NEW -add place name here-) It's confusing but, eh it's history. It's kinda like if an American Space Colony having the name New New York. There were a bunch of times what there were rumors of an Independent Mexico: William Lamport claimed he was a son of Phillip III (It was definitely a lie) and tried to have an independent Mexican Kingdom, José Sarmiento de Valladares, 1st Duke of Atrisco the Mexican Viceroy was rumored to have attempted to have the Spanish New World for the Hapsburgs during the War of Spanish Succession, etc. but the OP's original question was having a crown within Spain.
Just remembered the Aranda Plan (which has always struck me as Aranda having a beer with the King and saying WI we partition the empire with your sons as Kings? rather than an actual thought out plan). Seems to me, that would satisfy the OP: turn the vice royalties into Kingdoms attached to Spain with Bourbon 'kids' as Kings. Not sure if there were enough sons to do the job, or how Aranda envisioned it, beyond just a generic outline.