An unfinished manuscript by an Anglo-American merchant and politician, Benjamin Vaughan, provides a rare glimpse of the cartographic culture of the later Enlightenment. Vaughan reacted to William Lambert's nationalistic proposal (1809) for a prime meridian through Washington, DC, to symbolize both the Union's political coherence and its independence. Vaughan presented a more strictly nationalist and Enlightened viewpoint: there should be only one prime meridian (running through Palma, in the Canaries), chosen according to "natural" rather than political principles. Both viewpoints nonetheless rested upon a common appreciation of a map's "subliminal geometry" which equates the graphic space of the map with the geodesic space of the territory and the social and cultural spaces of human existence. This conception of the map has remained the basis for modern cartographic culture and its naturalization of the map, despite the rejection of Enlightenment philosophy. The prime meridian, as the defining and balancing line of space thus provides the avenue of mediation between the concrete state and the abstract nation. The debate over the choice of a prime meridian is inherently a discourse between competing political systems.