Kuby, Michael and Zhijun Xie. 2001. The Effect of Restructuring on U.S. Coal Mining Labor Productivity, 1980-1995.
Energy–The International Journal 26:1015–1030.
From 1980 to 1995, labor productivity in U.S. coal mining almost tripled, due to heightened competition, improved labor relations, scale economies, technological change, chronic oversupply, and industry restructuring. This paper uses EIA-7A data to analyze several hypotheses about labor productivity, which, if true, could signal slower future growth. The hypothesis that productivity growth may have been caused by closure of small inefficient mines rather than improvement of existing mines is evaluated by analyzing frequency distributions of productivity over time and by looking at a constant subset of mines that have operated continuously over the 16 years. Both methods strongly indicate that productivity growth has not just been the result of closing low-productivity mines. Other factors analyzed include depletion of thick-seam coal and tapering economies of scale—neither of which are strongly backed by the available evidence. Thus, continued productivity improvement is expected.