During the inauguration in 1857, a mysterious and lethal outbreak afflicted guests at the National Hotel in Washington, DC. The aftermath suggests a revision to the standard narrative of urban history in the antebellum years: a relatively smooth trajectory of improvement culminating in the prominence of experts during the Progressive Era. The response to the National Hotel sickness, in contrast, highlights the political tension attending this period—in one of the most planned American cities to date. The media fueled speculation about the disease to promote perceptions of bureaucratic incompetence, conspiracy, and mistrust toward city officials.