Thirteenth Child's Premises

I did not finish the book (lovely as all the world building was, I kept waiting for the plot to actually show up, and when it hadn't by halfway through I decided I didn't care), but I don't think you can.

Well, you could not read 1491

Which is shorthand for "not research the background to settlement patterns", which in turn feels like an odd thing to do when writing an AH which depends on just that sort of detail.

An interesting point of comparison is with Years of Rice and Salt, which starts out promisingly "different" close to the point of departure but seems to be warped forcefully by fate/the author into having a Renaissance and then a First World War roughly on schedule -- a parallel rather than a radiating history (which I also found rather unbelievable).

1491 is not necessarily the best background reading, from what I've read, but it is true that by all accounts, Wrede's worldbuilding doesn't take into account the logical ramifications of her change.

I don't think that I would make a claim for it as a basis for deep research -- it's by a journalist, after all -- but it's a useful pointer to the issues involved at this level.

It's more that it makes some equally improbable claims, and some Euro-centric assumptions, although at least it does address the "empty land" myth.

Presumably settlement would still be influenced by geography: beginning from natural harbors, moving up rivers and creeks, slowed by steep mountains, taking advantage of passes like the Cumberland Gap, clustered at sites of useful mineral deposits, or transport nodes like the meetings of rivers.

I didn't think that Thirteenth Child was all that great, but I didn't particularly see this problem with it. There are some differences in settlement patterns as compared to our world; e.g., its dangerous to cross the Mississippi, and the Rocky Mountains are more dangerous yet, because of magical creatures out west, so there's no city of Denver, and may never be one. There are also, it seems, some similarities, which can be accounted for on the grounds I've set forth.