When approached as a thing that facilitates relations between other things, an infrastructure need not be limited to the roads, rails, wires, and pipes typically conjured by the term. We can also understand it as a thing that facilitates other projects, a thing that expands flows, standardizes distributions, and extends political rationalities (Joyce 2003; Collier 2011; von Schnitzler 2013).

Yet as Brian Larkin (2013, 329) has recently noted, infrastructures are also things that exist apart from their purely technical functioning. They “need to be analyzed as concrete semiotic and aesthetic vehicles oriented to addressees.” That is, infrastructures do more than function or fail to realize the aspirations that established them. They put bodies in the path of things that hum, radiate, flicker, corrode, and lurch. They send them careening, changing their relationship to space and time. They raise the ambient envelopes of contemporary life, and they challenge us to understand the collective stakes of being emplaced within those envelopes. This is a productive challenge for anyone thinking through cities characterized by obsolescence—places in which broken infrastructures are common enough to be utterly unremarkable, even imperceptible.

Scholars have long implicated built environments (of which infrastructures are a part) in the constitution of collective social orders. Yet these environments are rarely considered communicative vehicles that address users in any conventional sense of the term, orienting them to shared attention, interpretation, and critical reflexivity. Quite the opposite: classic approaches (Mauss 1979; Bourdieu 2003) single out built environments as premier sites of rote reproduction, sites that inscribe shared meanings across the bodies of those who move within them. Scholars have recently expanded such views by tracing how collective social orders emerge from humans’ entanglements with the material world. Here, infrastructures are not just concretized aspirations, values, or meanings. They are fragile, unruly, and unpredictable assemblages of people and things (Bennett 2010). If it was once possible to treat infrastructures as dead or inert matter that humans bend to their will, it certainly is not now (Graham 2010).

Yet this emphasis on breakdown takes for granted something critical—the figure of user. This figure isn’t simply a ground that registers what functions or fails to function. She is also a body constituted within physical environments, including those undergirded by infrastructural complexes and whatever makes them up. Her capacity to notice these complexes, register their sensuous pressures, and recognize both as relevant to the life she shares with others is precisely what needs to be explained. The matter of any built form in urban social life is not so much matter per se, but rather a process by which the complicated entanglements of built form become a matter of collective concern (see Latour 2005, 31). One way to get at that process is to pay attention to the ambient envelopes that infrastructures form around urbanites. We need to track how these envelopes become broadly perceptible. And in places where broken—but also functioning—infrastructures distribute more and less than their designs envisioned, we need to recognize that the addresses of these infrastructures are sensuous and material at the same time.

Take a substance like lead, ubiquitous in older U.S. cities in the solder that still holds pipes together and the layers of paint that once made homes bright and durable. Its presence isn’t apparent. It is more often known by the havoc it wreaks on the bodies of children who ingest it. For them, lead can become a potent neurotoxin, implicated in everything from cognitive impairments to aggressive, even criminal behaviors. As health advocates, contractors, and parents explained it to me in the urban Midwest, what makes the ongoing presence of lead in older houses insidious is that it tastes good. Left unmaintained, leaded walls, windowsills, and baseboards could become sweet, poisonous lures for children. Yet adults, they insisted, should also take heed. Several contractors urged me to watch out for lead while following an effort that got underway in 2014: the demolition of sixty thousand obsolete houses in Detroit.

I would know I was “in trouble,” a thirty-six-year-old Chicago-based contractor advised, if the dust that drifted around demolished houses started tasting like the shitty candies and powders that coursed throughout our youth. In the urban Midwest, the tastes of Pixy Stix®, of Country Time® lemonade, of homes, of summers, of childhoods might become a metric of lingering harms posed by obsolete infrastructures.

It’s here that the metaphor of an infrastructure’s addresses needs some retooling. When taking into account an infrastructure’s components—functioning or otherwise—its addresses are also impingements. They play across the surfaces of bodies, even as they seep into them. Infrastructures form the ambient envelopes of urban life. Urbanites’ situation in those envelopes have consequences for how they understand their bodies to live, thrive, and waste within and beyond the places that have become them, and how they make claims about the collective harms and protections that might ensue.