Nineteenth-century telegraphy had a vital integrative role in the intersecting and mutually constituted developments of American industrialization, urbanization, and mediatization. Previous work by Tarr, Finholt, and Goodman¹1. Tarr, Finholt, and Goodman, The City and the Telegraph. focused on the internal activities of business, fire, and police institutions in American cities. Here, I move beyond their approach in relating telegraphy to broader infrastructural developments of national-level urban industry and modern mass media in the late nineteenth century and the rise of dominant, networked urban commercial, industrial, financial, and media centers. By radically accelerating the mobility of information and capital, telegraphy significantly reduced barriers of distance to industry, commerce, news and advertising, and state and military interventions. Owing to its commercial ownership in the USA, telegraphy privileged business over public use in comparison to Western Europe. Its enduring effects were its integrative functions in the development of a large-scale, urban-centered, largely private system of mass production, mass media, mass culture, and mass consumption.