From the end of the Civil War until the close of the nineteenth century, the United States Postal System grew into a vast communications network. The Post was one of the century's largest spatial systems, with more than 75,000 offices connecting communities scattered across the continent. Geography of the Post maps this behemoth network on its western periphery: where it spread, how it operated, and its role in shaping the space and place of the region. Analyzing the postal system in the West between 1867 and 1902 offers an entry point into some of the most important themes in late-nineteenth-century American history: the influence and reach of the federal government, the murky connection between public and private spheres, and the relationship between center and periphery within a national system of information. Geography of the Post sheds light on the communications infrastructure that stood at the very heart of American politics, economy, and culture.