A few readers have commented on similarities between Beyond Red & Blue's 10 States of American Politics and a 1981 book by Joel Garreau of the Washington Post called The Nine Nations of North America. Garreau's book, not surprisingly, made a big impression on me (certainly more than The Lord of the Rings or the misleadingly named Atlas Shrugged, both of which had adherents among my contemporaries). I have a yellowed paperback edition of Nine Nations at my desk right now; it's survived a lot of moving days. The book is out of print, but you can see Garreau's map on Wikipedia.
There are some differences between the two models, but also some geographical divisions that are still valid today. Garreau included Canada and Mexico and, unlike me, he did not set out to draw regions that were of equal size. He did not split any regions into two or more parts. And his emphasis was on economic conditions rather than political allegiances. My main quibble is with the Foundry region, which includes not only the industrial cities of Buffalo, Pittsburgh, and Cleveland, but also Chicago and most of the New York City area (he cuts out lower Manhattan and refuses to place it in any of his nine regions). Politically and economically, there is too much diversity in this area to qualify it as an entity. Even in 1981, Long Island did not belong with Flint, Michigan. Dixie was also too big, and parts of it are in four of my regions, though we both decided that Miami did not belong with Jacksonville and Memphis.
But Garreau's Mexamerica is basically the same as my El Norte, and the combination of his New England and Ecotopia is close to my Upper Coasts. If you're not familiar with his map, check it out, and let me know whether it makes more sense instinctively.