Texas/Anderson Territory: While this region seems to be very much in line with the wider Nomadic Herdsman/New Israelite culture, it is a feudal state. White has mentioned that pastoralism is not only an incidental way of life, but very much a moral one, and farmers are looked down upon. This might mean the area is occupied by thralls: Farms and villages where the Herdsmen are either the leige lords, or come around every once and a while to collect tribute (Much like Russia during the Mongol occupation.) The Andersons somewhat hypocritically enjoy the benefits of civillization while leaving peasants to do their dirty work. It's unknown if they subeject fellow New Isratelites to a double indignity, or they're a population of Non-Denominationals, Catholics, etc who occupy this rung. If so, this would suggest the faiths of Medieval America are a lot more pluralistic, and White's map merely exhibit the relgion of the ruling class.
Iowa:By contrast, Iowa is a realm that is slowly moving away their nomadic ways, and trying the embrace the culture of the East, and the split between the two sides of the Mississippi is one of a realm still in transition. The ruling family still has to make concessions to the nomads that buffer to the Great Plains, and it's also likely that it's a harder way of life to break away from. (White has mentioned horse archery was a lot more common at the beginning of the collapse, and it's also true that horse archery is a form of combat with a longer history in America.) It remains to be seen if the knights and castles thing is an invetiability for Iowa.
The Apppalachians: I've definitely mentioned this before, but while it's true pikmen are something familair to cities, in medieval times they're not out of place in rugged mountain areas, like the Alps or Scottish Highlands. Really, a lot of Appalchian culture is infromed by immigrants from Scotland and Ireland, and while the maps do say these areas are feudal states, they probably run very similarly to clans found in that time and place. They're not great places to wage warefare with horses, and the soil is probably not great for feeding them, or raising big feudal manors to begin with.
New Jersey: This "discrepency" was in many ways the thing that had be asking questions and creating this very blog. Both northern coasts of the continent are occupied by city states, martime republics, or ecclestical fiefs, in general a very urbanized, town-based society. New Jersey is a little different in that it's clearly a feudal state, and it probably is a little more agrarian than the rest of the region. However, it does boast the largest city in the Northeast, (Phialdelphia), and the distance between it and Trenton looks to be the shortest distance between two cities. So I constantly wonder what New Jersey society is like, where it has a lot of leige lords, but relatively little knights. It's actually quite logical in a lot of ways, as Jersey is kind of compact and hemmed in, and probably fights more defensive, seige-based warfare. It's quite possible it just hires a lot of mercenaries from the rest of the region, people from the Appalachians or New Englands who have come to greener pastures to find their fortunes. I've actually also kicked around the idea of New Jersey resembling Ancient Sparta--many considered a little more feudal than the nearby Greek City states, and at times had to be prodded into improving its naval capabilities.
United States: Something I've mused on many times is why the Delmarva Pensisula is so heavily knight-based, even though the U.S. is a Republic, a thalassocracy, and the pensinsular itself being a little cut off. I've always wondered about the practical use for this as well as the logistics, but it certainly keeps the area defended. From an aesthetic point of view, it is kind of neat to imagine knights carrying the U.S. Federal banner to be something like a cross between the American Civil War and the Crusades.
In summation, I think all these sort of distinct, quirky units (Feudal Texas Archers, New Jersey Pikemen Lords, U.S. Federal Knights), all deserve their own sort of name, made up whatever new language arises in Medieval America. Also of note it that the secretarial states also have their own knights, though I'm not sure if they are particularly different from the rest of the nights found in the Deep South.
