So how big are the cities in White's World? What are the most prominent?
New York and Los Angeles are the primary cities of the current U.S., and the second largest are Chicago and Houston. (Occupying the "other" two coasts) All four cities seem to see a downgrade in Medeival America. This is largely because these cities have benefitted from interconinetal trade, whereas the oceans feel a lot more vaster in the Medeival world, and trade has to be conducted closer to home. America, in particular, can't be a clone of Europe most of the time because there's simply no great counterparts to the Meditarrnean. All inland seas are in places that are too cold too dry, or too swampy. Therefore, the biggest cities are located on rivers.
So what are the absolute most major cities? The most populated? Maps indicate they would be Cincinatti, Portland and New Orleans. The next tier appears to be Buffalo, Sacremento, Philadelphia, and possibly Houston and Augusta. Interestingly, the latter two cities are not considred trading hubs, while the smaller Salt Lake City is. New Orleans itself may be the most populated city in America--it's certainly the gateway between the Mississippi River and the open ocean.
I'm also curious as to what District Capitals and "Major Fortresses" look like. These are towns which may or may not have large populations, but it seems they have a degree of importance despite size or trade convenience. In reasonable-sized cities like Nashville and Boston, there's probably a good deal of prestige combined with political power. Towns like Lexington and Dover may be glorified abbeys.
We may see less "special" cities out in the west. The "special" communities are very likely the nomadic villages, or cities with the strange monuments that are hallmarks of the Hydraulic Empires. However, there are settled communities in Arizona, but no named cities. I would frankly like to know what they look like.