Iowa is the number one ethanol producer in the country with 43 ethanol refineries and an annual existing production capacity of 4.2 billion gallons, plus an additional 120 million gallons of production capacity reported under construction at the end of 2017 (RFA, 2018). In 2017, Iowa’s ethanol plants produced a record volume of 4.2 billion gallons, increasing 2.4 percent from the previous year (4.1 billion gallons). Annual ethanol production data up to 2017 at the national level is available (Bioenergy Statistics, USDA-ERS); however, at the state level data is available up to 2015. Iowa’s historical share of U.S. total ethanol production from 2010 to 2015 (26.8 percent) was applied to 2016 and 2017 U.S. ethanol production to estimate Iowa’s production during those two years.