As trading of agricultural crop futures contracts evolved in the 19th century at the Chicago Board of Trade (CBOT), there were futures markets for wheat, corn, oats, rye and hay. In the 20th century, trading in the hay and rye markets diminished so much that the CBOT eventually dropped them. However, emergence of soybeans as a major crop prompted the CBOT to create futures contracts for soybeans, soymeal and soyoil, which attracted enough trading volume to become very successful. Grain exchanges in Kansas City and Minneapolis then used those as models when they created futures contracts for the specific classes of wheat commonly produced in their geographic areas. Trading volume for Kansas City and Minneapolis wheat futures contracts was re...