Two of the major trends shaping the evolution of agriculture in the United States are reduced diversification and increased risk in grain-crop production. This paper will attempt to document these trends since 1950, with data for one state, Minnesota. Since the state produces no cotton, rice, tobacco, or subtropical fruit and vegetable crops, there can be no pretension that it represents the full range of land use in U.S. agriculture. Minnesota has been a significant producer of all of the principle grain crops, livestock products, sugar beets, and oil seeds, and it bridges the boundary between the dairy belt and the grain belt in the Mid-West. With these limitations, Minnesota data provide revealing evidence of changes over the half-century since World War II that are redefining the structure of American agriculture. The primary data sources are the time series of annual data maintained by the Minnesota Agricultural Statistics Service, supplemented by data from annual studies of the Minnesota rural Real Estate market, conducted by the University of Minnesota.