In 1883, the San Antonio Daily Express published a series of letters written by special correspondent Hans Mickle. The reporter was exploring parts of the new transcontinental railway that ran across the American Southwest, connecting San Francisco and Los Angeles to New Orleans. As he followed the route that raced westward across Texas from San Antonio, he entertained his readers with descriptions of the foreign landscape and the assorted passengers that caught his attention, including the “Chinamen” who filled the cars on their way back west, he presumed, to San Francisco and China. Mostly, however, Mickle wrote about El Paso, which according to his report was “the most western point in Texas, and is Texan only in name, as, in almost everything else, it has few Texan characteristics.” If not characteristically Texan, though, El Paso came to represent something even grander for Mickle, for at the “extreme head of an extensive valley,” in a pass flanked by high and rugged mountains, he found himself standing in what he called the “Future Immense.”...