Ws WHEAT and flour are known to move in large volumes V from region to region in the United States. Knowledge of this trade stems from many bits of particular information on topics such as the location of flour mills and the location of wheat production, and from general information, such as the notion of advantage. Statistics are not available, however, which would allow direct mapping of interregional patterns of trade. In the present paper, the question is asked: to what extent can patterns of trade in wheat and flour be projected from available techniques and information? Certainly, the most general thingknown about trade is that the location of production and the location of trade flows are determined simultaneously: production is determined by possibilities for trade and trade is determined by the location of production (and consumption). But in the case of a resource-based activity such as the production of wheat and subsequent milling of flour, it is known that variations in natural resources exert a profound effect on the location of production. Too, it is known that the location of the ultimate market is not greatly influenced by the location of wheat production. So, in the short run, our general information about trade in wheat and flour allows us to take resources, production patterns, and ultimate markets as given. Concern is ch efly with the balance of flows between production regions, processing mills, and market regions. The term comparative has been used as a succinct explanation of problems of trade flows, but usual elaborations of advantage do not completely describe the present problem. Usual statements of advantage refer to two commodities exchanged between two locations. In the wheat and flour case, concern is with the flow of a basic commodity and one of its products among many locations. For another thing, discussions of advantage usually ignore transportation costs between locations, and specific recognition of transportation costs is extremely important to the present trade formulation. In this study, the concept of spatial equilibrium is used to project trade patterns. The concept treats trade as an outcome both of regional differences and transport costs among regions, and brings together bits of information observed from place to place, in order to project movements of wheat and: flour. In the first portion of this