Urban areas have been the main source of pollution for centuries. The United States is no exception to this more general rule. Pollution of air, water, and soil only multiplied as cities grew in size and complexity; people generated ever more domestic waste and industry continually generated new unwanted byproducts. Periods of pollution intensification—most notably those spurts that came with late 19th-century urban industrialization and the rapid technological innovation and consumer culture of the post-World War II era—spurred social movements and scientific research on the problem, mostly as it pertained to adverse impacts on human health. Technological innovations aimed to eliminate unwanted wastes and more stringent regulations followed. Those technological and political solutions largely failed to keep pace with the increasing volume and diversity of pollutants industrial capitalism introduced into the environment, however, and rarely stopped pollution at its root cause. Instead, they often merely moved pollutants from one “sink”—a repository of pollution—to another (from water to land, for instance) and/or from one place to another (to a city downstream, for instance, or from one urban neighborhood to another).
This “end of pipe” approach remained overwhelmingly predominant even as most pollution mitigation policies became nationalized in the 1970s. Prior to that, municipalities and states were primarily responsible for addressing air, water, and land pollution. During this post-World War II period, policy—driven by ecological science—began to exhibit an understanding of urban pollution’s detrimental effects beyond human health. More broadly, evolving scientific understanding of human health and ecosystemic impacts of pollution, new technology, and changing social relations within growing metropolitan areas shifted the public perception of pollution’s harmful impacts. Scientific understanding of how urban and suburban residents risked ill health when exposed to polluted water, air, and soil grew, as did the social understanding of who was most vulnerable to these hazards. From the nation’s founding, the cumulative impact of both urban exposure to pollutants and attempts to curb that exposure has been unequal along lines of race and ethnicity, class, and gender. Despite those consistent inequalities, the 21st-century American city looks little like the 18th-century American city, whether in terms of population size, geographical footprint, demographics, economic activity, or the policies that governed them: all of these factors influenced the very definitions of ideas such as pollution and the urban.