The world of The Sharing Knife is post-post-apocalyptic, as in gone back to nature, mostly. The major river from Passage, the Grace, has been compared to the Ohio river in author notes, which is a tributary to the idenitically-laid-out Gray/Mississippi river. The big dead lake on the north end of most maps was said to have once been a chain of lakes, with 'straight' roads around them made by the sorcerer-lord Precursors. I keep coming back to the suspicion that this world is actually the post-apoc version of the North American Midwest, around about Ohio and Indiana. The Ogachi Strand is the ruins of Chicago, and like other modern major cities, was easily several miles across. Michigan is buried in the crater of the Dead Lake, or was destroyed in the blast that merged the Great Lakes. The malice-blight is easily seen as a form of radiation, leeching life-energy from the land. Lakewalker magic is easy to justify, depending on your favored flavor.