The article explores the relationship between regulating traffic and structuring congestion in mid-nineteenth-century London. It examines plans for the opening of new streets and for the erection of dedicated structures such as subways and pedestrian bridges, as well as the debates around legislation regulating everyday practices, which included the introduction of time intervals and designating pedestrian street crossings. The need for people and vehicles to circulate was central to all of these as were the reactions against congestion. The article interrogates the extent to which the study of what might be termed circulation’s inextricable other, namely congestion, sheds a new light on our understanding of the experience of modernity at a particular time in London’s history.