Reply to Matt &c
Matt, thanks for the insightful comments!
I guess my answer may not satisfy you, but I had a certain rationale behind it...
The ommission of mention of Canada, Quebec, Columbia is not necessarily indicative, it is more because it did not come into the realm of the subject matter that the "author" was describing - ie any focus on a potential clash of the dominions of Missouri and America is focused on using the Indians in the former, and on the "naval frontier".
Border states serve the interest of the home governments, so the Shawnee as a British puppet between America and Missouri, and Comancheria as a French puppet between Missouri and Spanish Mexico. Relations are governed by treaties, which would allow urban settlement, development etc but not the dispossession of the land. Comancheria being larger is more of a federation of chiefs, probably including Apache as well as Comanche.
Another thing not to forget is just how large the settled areas of these Americas are - Mississippi seems to have as many counties as England! A greater focus on building up the infrastructure in these areas, and policies which encouraged this, would have seen much higher population density. Look at that of some European cities of the time, and then transplant some of these into Wilmington, Savannah, New Orleans etc.
In addtion, British colonies and dominions would largely be for citizens of Britain to migrate to, French colonies and dominions for those of France, Spanish for those of Spain and so forth. While there would of course be cross-border movements within the dominions themselves, there would not be so much of an influx of Italians, or Germans, or Hungarians. It would be more likely that an older pattern of Germans or Hungarians moving into an expanding Russia would continue.
In addition, both Turkey and Egypt would be more foreigner-friendly, whilst Britain, France etc has client states around the world that would also see some significant immigration, perhaps rather more of the merchants, military veterans, planters, and adventurers rather than the ordinary economic migrant. The Kingdom of Sicily boasts both a permanent British naval base at Messina, and strong British support for its monarchy, and can be expected to have seen some significant movement of capital from Britain, followed by that of British businessmen, merchants, adventurers and so on, including relatively small entrepreneurs, just as Chile for example did in the mid 19th century when many a visitor remarked that Valparaiso seemed more to be a British colonial city than a Chilean port.
Floridia will have seen an influx, or perhaps waves of migration, since achieving its independence, simply because as a new state with lots of land and relatively few population centres it would have been far more welcoming to the immigrant willing to turn swamp into farmland, beach into town and so on.
I certainly don't think that Missouri has a policy AGAINST settling the Indian lands, but it would have a much larger settlement focus along the Mississippi, rather than further out, and again it would have a much higher population density here due to this.
In general, relations with the Indians are governed by laws enacted at the imperial capitals, London, Paris and Madrid, rather than in the dominion capitals of Philadelphia, New Orleans or Mexico City, and for obvious reasons as you make clear - local legislatures push the limits of laws, then subvert their own laws, then change them. I don't necessarily give the Georgian Cherokee population much chance except to assimilate into being American citizens (which was already well underway by the time of the Trail of Tears as evidenced by the fact that a fair number of Cherokee were EXEMPT because of their US citizenship), but if they are driven from their lands, it will be by aggressive sales techniques, and any who choose to sell up and remove themselves are far more likely to move to the Shawnee state.
The Shawnee were always a confederation involving other displaced tribes, and as an independent vassal state would become the natural point for any Indian wishing to remain Indian in his heritage to remove himself to; thus Cherokee, Creek, Choctau etc would all end up there, unless they wished to be assimilated or unless they came by sufficient wealth to avoid assimilation, since like the vast estates of nobles sold off due to inheritance taxes, money talks and if the Indians cannot afford to hold onto their land, then they will eventually sell up.
The same would be so within Missouri, except that the lands of the Sioux, Assiniboin, Kiowa, Arapahoe, Cheyenne etc have not been so encroached upon as to displace the ruling Indian elite.
Non-wars between bordering populations will also be a thing of note - there will have been numerous skirmishes between militias on the America-Missouri border, all of which would be settled in Europe, and referred to neutral arbitration if necessary. The Battle of Atchafalaya Bay is just this on a much larger scale. Hotheads in Philadelphia and New Orleans might have been ready to go to war, but neither London nor Paris can contemplate a global war over such an issue.
As a note, I would also say that the absence of population in an alternate-history country does not mean either they all went somewhere else, or they all suffered a horrible death, as population is, to a degree, linear in its growth.
If children are not born to a segment of the population in Generation 1, then Generation 2 of these children is not born either, nor is Generation 3 from Generation 2.
This is not completely linear because consider that Man A marries a woman from Generation 2, and Woman B marries a man from Generation 2. If we remove these Generation 2 individuals, Man A can still marry Woman B, so it is not strictly speaking the case that the removal of Generation 1 removes the NUMBER of all descendants.
However, by Generation 4 your Alternate History Timeline could be showing a million people not living in the country they did historically live in. But these million people have not gone elsewhere, nor have they all died in misery and poverty, they simply were not created due to statistics.
Alternate History Fiction Yuku board
Grey Wolf Web Design