Everyone has a story about the Post Office. Sometimes the story is endearing—the mail carrier who becomes like a member of the family and brings treats for the dog every day. Sometimes it is a cautionary tale of bureaucracy run amok. Either way, the ubiquity of interactions with the Post Office marks its centrality in American life. Yet for scholars, that presence means that the postal system can be easy to overlook when they examine government and society. Or to put it another way, “when something is everywhere, it can start to become invisible” (4), as Cameron Blevins introduces the postal system in Paper Trails. A stunning work of scholarship, Paper Trails explores how the US Post Office shaped the American West and the federal government's structure during the nineteenth century.The key, according to Blevins, is that the postal system created a “gossamer network,” a metaphor that suffuses the book. Rather than creating a rigid, top-down infrastructure, the postal system in the West developed as a series of webs, interconnected and constantly changing to meet the needs and demands of residents, officials, and the federal government back in Washington. To make his case, Blevins constructed a database using geographical information about tens of thousands of post offices created or eliminated throughout the nineteenth century, allowing him to visualize the growth and extent of the postal network with precision across a broad chronology.Through seven chapters organized in rough chronological order, Paper Trails delivers a fascinating view into how the post office integrated the West into the United States. In addition to establishing offices, the Post Office undertook a significant (though chronically underfunded) effort to map the hundreds of routes crisscrossing the nation—which became the cartographic tools of choice for nearly all other federal agencies after the Civil War. Likewise, Blevins explores the advent of the money order system, another innovation of the Civil War that allowed people to send sums securely across vast geographic distances. In a region that lacked not only extensive banking but also significant currency circulation, money orders became a tenuous lifeline that westerners used at double the rate of their eastern brethren, primarily to engage in regional and national commercial life. And though this institutional history necessarily offers a limited cast of characters, Blevins colors his account with the stories of numerous individuals whose lives and careers shaped (or were shaped by) the US Post Office.The result of Blevins's meticulous work is a significant contribution to debates about the formation of an American state in the nineteenth century, the nature of federal power in the West, and the role of digital history as a research method. In particular, Blevins argues that understanding how the American state formed must take more careful consideration of geography on a granular level. On one level, he accomplishes this simply by shifting the lens away from the halls of power in Washington, DC, but the point extends further. The state not only existed outside the capital, it also drew much of its organization and eventual power from its development as a decentralized and contingent network. Because so much of the postal system's infrastructure was based on contracts with individuals to operate an office in their town, its presence often appeared locally as “a fleeting entity capable of popping up and then quickly melting away along with the fortunes of a local business owner” (48).Digital history is no longer a new methodology, though the most recent decade has seen remarkable advances in the tools available. Even so, scholars—including Blevins himself, in “Digital History's Perpetual Future Tense” (2016)—have engaged in a lively debate about whether digital history will eventually deliver on the promise of historiographical interventions in addition to its introduction of a plethora of methods for historians to analyze massive sets of historical data. Paper Trails emphatically declares that such interventions are indeed possible, even as Blevins displays facility with a range of digital tools. He displays these through forty-nine stunning figures, most of which visualize the geographic implications of the book's argument. They not only illustrate but clearly advance Blevins's case for the relationship between state formation and the Post Office, showing in minute detail how the Post Office opened and closed offices, where it utilized government employees versus private contract labor, or how individual Americans used the money order system, to give just a few examples.Blevins, a diligent scholar and writer, carefully documents the limitations of his methods—not least of which is that the data sets for nineteenth-century post offices occasionally require rough approximations for the locations of specific offices. That self-awareness, alongside the extensive research, make Paper Trails a model of digital history methods and historical writing.