This dissertation analyzes designers’ efforts to visualize ecological aspects of freeway infrastructures amidst the 1960s freeway revolts. From the postwar years through the 1960s, U.S. freeway plans catalyzed a public reckoning regarding the natures of cities. Government officials, urban dwellers, and designers and planners across the United States debated the infrastructures’ placement, wrangling over the values of threatened sites and neighborhoods. Through these debates, prior conceptions of urban environments expanded to encompass the dynamic, living, and inter-relational dimensions of cities. This transformation took place via public discourse, and also through innovative design approaches, as architects, landscape architects, and urban designers engaged freeway designs as opportunities for technical and methodological experimentation. Mixing earlier generations’ parkway visions and concerns for spatial experience with emergent cybernetic themes, data-driven analysis, scientific references, and anticipations of computerization, these explorative designs modeled natural forces in new ways, and at new scales. The following chapters examine freeway projects by Lawrence Halprin, Kevin Lynch, Donald Appleyard, Christopher Alexander, Ian McHarg, and others, drawing on frameworks from environmental history and science and technology studies to interrogate how freeway design processes engaged public controversies and modeled human/nature relationships. The chapters advance in time and scale, showing how conceptualizations of the urban environment shifted with changes in drawing implements, uses of eyes and hands, inclusion and exclusion of data, and designers’ understandings of their roles relative to living forces. The resulting fine-grained account charts how urban infrastructures, environmental ideas, and design practices evolved together from the mid 1950s through the late 1960s: tracking the evolution of urban environmentalism, elucidating sensorial aspects of freeways, and scrutinizing the political advantages and cultural complications of visualizing landscapes through data-based quantification. This text makes designers’ roles in environmental movements more accessible to a broad range of scholars. It contributes to an emerging transdisciplinary discourse regarding environmental histories of design, and forges new ground at the intersection of literatures on ecological design, architectural drawing and making, urban environmental history, and science and technology studies. Above all, it articulates what is at stake – socially, politically, and environmentally – in how designers engage the many skilled actions of designing.