Aesthetic visualization projects that incorporate users, community stakeholders, multiple modalities and technologies emphasize the way that an artistic visualization can be both an artifact and a process—a conceptualization of aesthetic visualization that is useful for thinking about visualization in general. In this article, the authors propose the concept of the visualization as boundary object, a move away from the indexical claims of visualization and instead toward an acknowledgment of the entangled nature of social, political, economic, cultural, technological and environmental actants. Through a description of the In the Air, Tonight public visualization project, the authors suggest that by making manifest the connections between these actants, a visualization project, as a form of expressive cartography, can contribute to the visibility of and engagement with important issues (e.g. homelessness) that affect society.