The Metabolism of the Industrial City: The Case of Pittsburgh

The concept of metabolism has been adopted from biology and refers to physiological processes within living things that provide the energy and nutrients required by an organism as the conditions of life itself. These processes can be described in terms of the transformation of inputs (sunlight, chemical energy, nutrients, water, and air) into biomass and waste products. While essentially a concept originating in science, I have found it useful as a means to comprehend the environmental history of cities. Just as living things require the inputs mentioned above, so do cities. That is, cities cannot exist without those inputs—urbanites require clean air, water, food, fuel, and construction goods to subsist while urban industries need materials for production purposes. These materials may initially come from the area of the urban site itself, but increasingly over time they are derived from the urban hinterland or even farther. That is, as the city grows, it extends its ecological footprint deeper and deeper into its hinterland.