The article deals with the relationship between media and transportation infrastructures and analyzes their links to the concept of mobility. It examines the assumption that infrastructure systems themselves are mobile, in the sense that they develop and have to be maintained constantly. According to such a perspective, they are to be considered not primarily as “structures,“ but as specific processes of mobilization (infrastructuring) that constitute the basis for mobility in the sense of transport and movement. Drawing on historical knowledge of transportation, it will be shown that a broad understanding of traffic as exchange, communication, and transportation has narrowed in the twentieth century, whereby the originally implied idea of transport as transformation became suppressed. Recent approaches in mobility studies, Science and Technology Studies (STS) and Actor-Network-Theory (ANT) can be combined in a fruitful way to unfold the specific dynamics of infrastructure as a process of mobilization (Callon) and technical mediation (Latour).