 In 2012, Iowa farmers produced 18.3 percent of the nation's corn, while Illinois produced 15.3 percent.In 2011, there were 13.7 million harvested acres of corn for grain, producing 2.36 billion bushels, which yielded 172.0 bu/acre, with US$14.5 billion of corn value of production.Wheat is produced throughout the Midwest and is the principal cereal grain in the country.