Walking Old Tom's Grand Grid

Chase County, Kans., writes William Trogdon, "is the most easterly piece of the American Far West." Meaning what? And who, for that matter, is Trogdon, whose name does not appear on the title page of his extraordinary and wholly original new book, PrairyErth (a deep map)? What's prairyerth?

One question at a time. Prairyerth is an old geological term for prairie soil. The westerly thinning-out of forest and the first broad stretches of prairie grass are what make Chase County a magical place for the author. Eastern travelers feel edgy here, Trogdon notices, and so do some natives: "The protection and...