The purpose of this paper is to review past trade relations in the grains sector between the United States and Canada and to document trade barriers and the potential for the evolution of reciprocal trade. Historical trade flows between the United States and Canada in the grains sector are reviewed. Terms of recent trade agreements and other trade restrictions are described. Then, some of the important differences in the marketing system are described and compared as well as changes in the Canadian grain marketing system. Finally, the concept of reciprocal access is developed in the context of the evolving trading relations between these two countries.