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Figure 22.2 Processed flows for physical goods in the USA, 1900-96

I | Renewable organics I | Non-renewable organics □ Metals I | Minerals

Great depression

Recession

Oil crisis

Figure 22.2 Processed flows for physical goods in the USA, 1900-96

embedded in imports and exports of finished goods have not been considered. For some processed flows these can be significant but, overall, for the USA they are small in relation to total flows (Matos and Wagner 1998).

It may be noted that the total for the processed physical goods presented in this section is somewhat higher than that presented in the earlier section: 2957 million versus 2487 million. This arises from the fact that more commodities were included here, the previous data were for outputs and additions to stock, resulting in deductions having been made for recycled flows, and in some cases different data sources were used.

On the basis of these figures a number of observations can be made. Overall, during the 20th century processed flows for physical goods in the USA rose exponentially, at a rate much faster than population, with fluctuations during business cycles, until about 1970, at which time a temporary leveling off occurred. During the last two decades of the 20th century, overall flows for physical goods once again appeared to rise faster than population. During the century, the annual use of physical goods in the USA increased about fivefold, from two to 11 tons on a per capita basis, and increasing amounts of material were obtained from non-renewable resources, dominated by the minerals category which includes the massive flows of crushed stone, sand and gravel. While flows from each source increased during the century, the rates of increase differed markedly.

Table 22.3. provides a snapshot of per capita use at the beginning and the end of the century. Increases occurred in all but one resource category, and there are considerable differences in what was used then and what is used now.

Within the minerals and metals categories (Figure 22.4 - underlying data in Table 22A.2), the rate of growth in construction minerals flattened after the completion of the interstate highway program in the 1970s, dipped in response to the recession in the early 1980s, and currently appears to be rising again. Metals use, dominated by steel, generally grew during the century but leveled off, declining slightly, from 1975 until about 1991.

Figure 22.3 Processed flows for physical goods in the USA, 1900-96 (log scale)

Table 22.3 Sources of physical goods in the USA

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