Abstract This article addresses the question of whether soybeans, soybean meal and soybean oil produced in the USA and exported were part of a single, world geographic market during the decade of the 1980s. An answer to this question is sought using an approach to defining a geographic market based on the notion of instantaneous causality. The empirical results, based on prices for soybeans, soybean meal and soybean oil for three spatially diffuse locations, suggest that there was but a single identifiable world market for these commodities over the period of study. This has implications for the continued presence of soybean production subsidies and discussions on international agreements designed to reduce or eliminate these subsidies.