The Princeton Collections of Western Americana recently acquired 36 nineteenth and twentieth-century folding pocket maps of the American West (primarily published by Rand McNally). With the exception of Texas and Hawaii, every state West of the Mississippi is represented, including Alaska, and the dates range from 1891-1930.
The pocket books contain indexes of counties, cities, towns, and villages, as well as post offices, railroads, electrical lines, and telegraph and mail services.
Along with the maps and indexes, the pocket books also have advertisements for tourists, such as The Santa Fe Southwest Enchanted Land advertisement shown above, and multiple advertisements for products targeting the weary traveler (and likely the traveling salesman).
To find these and other Rand McNally holdings in the Department of Rare Books and Special Collections, see: Rand McNally and Co.