This dissertation explores how maps and architectural landscape renderings function as rhetorical devices in support of changing understandings of urban-nature relations. Arguments around these changing relations to urban nature are investigated through a comparison of visual materials, specifically maps and renderings of Los Angeles River projects from the early 20th century through the early 21st century. These materials include engineering maps of flood control infrastructure, diagrammatic maps produced by river advocates, and landscape architectural renderings used in river revitalization master plans. The different qualities of these materials support a shifting social relation to the river, in addition to arguments made for constructing a flood control channel, water conservation infrastructure, or riverfront bicycle paths. I developed an infrastructure typology that delineates three different ways of understanding the role of the Los Angeles River over time: 1) as primarily a flood control channel, 2) as a multi-purpose channel within a watershed ecology, and 3) as the site of a waterfront linear park running throughout the city. Archival research in the collection of the Friends of the Los Angeles River (FoLAR) papers and semi-structured interviews with several key river revitalization and environmental advocates deepen the understanding of the work that maps did in shifting social relations to the river. Maps and visualizations of the Los Angeles River are chosen because they advocate for substantially different functions of the river (arguing to concretize it for flood control or remove concrete for habitat preservation, for example) prior to any changes on the ground. In this way, visualizations serve as rhetorical devices rather than representations of what is on the ground.