Random musings I feel the need to write for some reason, even though this universe runs on Rule of Cool:
The agriculture-herding boundary is a couple hundred miles too far east. Even without the aquifers of recent centuries, rainfall should be enough on its own to sustain at least moderately intensive agriculture, a sedentary society supplemented by animal husbandry, into the eastern thirds of Nebraska and the Dakotas, half of Kansas, and so on. Especially since the rain line has been shifting east recently, probably due to climate change, and with that out of the way it should stabilize somewhere between the 99th and 100th meridians west. Even if mounted archers can outfight farming societies in marginal areas, eventually sheer numbers will tell. So the cowboys should be restricted into a fairly narrow band between thereabouts and the Rockies, with Iowa safe from their raids in all but the worst times (once in a lifetime, say), and the Mississippi impassable unless they have all, not just one particularly powerful band, been united under a reincarnation of Temujin.
Kuluradu should not exist. Even if all the Muslims in the entire decaying federal prison system were at Florence, and even if they all staged one coordinated riot during a distracting crisis, they'd eventually get outshot by local forces, who wouldn't take kindly to a surely despised foe going on the rampage. Prisoners with stolen or makeshift weapons should be no match for posses, national guards, and sheriff's departments, even in favorable circumstances.
The USA should still be in D.C. In an age where the government would be hyper-sensitive to the symbols of legitimacy, going to Baltimore would only weaken their claims. Giving the entire city to the Non-Denom Church would be like the Byzantine emperors decamping to Nicomedia and leaving Constantinople to the Patriarch. I get what White was trying to do with the Rome analogy, but that happened when the city split off from the Byzantines in the 8th century because the empire couldn't force them back into line or protect them. With the US government still controlling the area all that'd happen is that the Chief Justice who proposed such an idea would wake up dead.
California would not have adopted the Desereti alphabet. California is a larger, richer realm, not the type that would normally just adopt a whole new writing system for ease of trade. Especially since the Desertis are rivals and infidels ("suppressives"?) In fact, I'd expect the relationship to realistically go the other way, with the Desereti alphabet being restricted to ceremonial purposes and most writing even within Deseret happening in some kind of demotic hybrid or Deseret-influenced Latin, but I'll let that slide..
These all strained my suspension of disbelief.
Lesser implausibilities that are a bit weird but not too egregious:
New Age New Mexico should probably be New Age-flavored Catholicism instead.
Scientologist California. There's roughly 20,000 of them in the state in 2019. The demographics almost certainly just aren't there, except maybe for Scientology-influenced syncretism if they get lucky.
Although it was done cleverly, I feel that the effective end of race in the South (everywhere else is too monochrome to sustain separate racial identities, as White notes) is still unlikely. If race is in the rest of America's DNA, in the South it's a ritual scar.
On a similar note: the de jure acceptance of debt bondage by the Supreme Court. It would be too open for the north, which would still semi-hypocritically pride itself on greater adherence to American values of equality of opportunity. I expect that there'd just be a gag rule on challenging it, but the north wouldn't have to accept it, much less have it.
Thoughts?