If 30,000 people were killed each year in the United States by a curable illness, we would call it a public health crisis. We would deploy resources, vaccines and interventions to address the spread and bring the death toll to the only acceptable level: zero. Yet, every year 30,000+ people are killed in preventable traffic collisions in this country. Vision Zero asks us to see those traffic deaths like polio or cholera: epidemics that, with an urgent health framing and public response, can be eradicated. In this case study we explore how San Francisco, New York City and Chicago are using the tools of public health — including epidemiology, research and a focus on the root causes of health inequities — to advance their Vision Zero efforts.