Ethanol refineries locate near feedstock sources: Corn is the feedstock for 97 percent of the ethanol produced in the United States, so refineries are heavily concentrated in the Corn Belt. Ethanol must be shipped long distances, usually by rail, to reach the major fuel markets on the east and west coasts. Refineries also locate near markets for coproducts such as distillers’ grains, which are sold as feed to the livestock industry.
(source: usda)