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Detailed information on coal transportation is a necessary and important element of energy policy formulation. At the intrastate scale comprehensive information is often difficult to collect because of industrial confidentiality. In order to test the accuracy of publically available data, origin-destination movements of utility coal are estimated for Pennsylvania, using a maximum-entropy model of spatial interaction. A series of models is evaluated incorporating assumptions on transportation cost and mode, connectivity of origins and destinations, and coal properties. The inclusion of contract arrangements through restricted connectivity produces the greatest improvement in estimated flows. Attempts to specify a general cost function by the addition of coal properties (Btu. sulfur, ash l produces no significant improvements in the goodness-of-fit. The paper concludes that the identification of unobserved transport cost data by the method of residuals meets with mixed success. The results indicate that separate calibration of large-volume flows is a useful direction for further study. [ABSTRACT FROM AUTHOR]