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downwind, downstream, downtown: the
ENVIRONMENTAL
LEGACY IN BALTIMORE AND MONTREAL
SHERRY OLSON
ABSTRACT
For two centuries, each surge of city-building has consumed massive amounts of raw materials and restructured flows of materials, as merchants and manufacturers reached out to capture resources from greater distances but persisted in accumulating a large share of the wastes close to home. Eight such surges of growth can be seen, and synchronized, in Baltimore, Maryland, and Montreal, Quebec. The environmental impacts are marshalled to appeal for more attention to material flows at scales that reflect the boom-and-bust context of urban decision making.
| CHANGES IN THE METABOLISM of the city—the rate and efficiency with which it transforms energy—arise from changes of scale: the size of the population, the area it occupies, the resource areas it taps, and the sinks available for waste disposal.1 We experience such changes as everyday problems: smog, wheezes, overflowing drains, and overflowing dumps. Great efforts are underway to assemble global and national assessments of the balance of heat, nitrogen, or CO2, and, with a rising sense of urgency, citizens work at assessing their individual "footprints." As a complement to these metrics, I argue for more attention to material flows at the geographic scale of the metropolis and on a time scale cognizant of its boom-and-bust construction. |
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There are three reasons for considering the scale and tempo of urban growth. First, massive amounts of energy are baked into buildings and roads, or spent on transport of their materials. This energy is expended in great bursts, in a powerful rhythm known as the Kuznets cycle, with a period of fifteen to twenty-five years. The construction cycle is well documented for North American cities, but its effects have been neglected in both urban and environmental history.2 What we build in the span of four or five years creates a stream of future demands for operation and upkeep. Since the 1820s eight such surges have produced critical changes—of distances, densities, volumes, and surfaces—that modified the rates at which materials were subsequently required. |
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Second, the net direction of material flows in the North American economy is toward cities. Merchants and manufacturers repeatedly reached out to capture inputs from greater distances, but persisted in accumulating a large share of their wastes close to home. The pattern of flows that distinguishes a particular city today was modeled—and remodeled—in the creation of its infrastructure. Each surge of growth reengineered the hydrology and energy balance within the city, in the surrounding region, and at remote sites of exchange. We need to examine more systematically the effects of each surge of growth on habitats downtown, downstream, and downwind. |
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A third reason for disaggregating analysis to urban dimensions is political. It is at the scale of the polis that impacts of material flows—the magnitudes and technological options, the economics, and the chemistry—can best be grasped without losing sight of the personal implications for city-dwellers: their health, life chances, range of choice, and sense of agency. Instrumental to each surge was a "growth machine" that enlisted builders, suppliers and shippers, lenders and speculators, property owners, and local governments dependent on property tax.3 A local growth machine was reassembled in each generation, and in the resistance or acquiescence that we observe in the municipal arena, we can explore relations of power without losing sight of human faces. |
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