Concentration of corn and soybean production in the U.S.
Seventy-five percent of U.S. production is produced in 456 counties, the above 220 counties plus 236 more counties. These 456 counties are predominately in the Corn-belt. In addition to the states with counties that account for 50% of production, additional states with counties in 75% of U.S. production include Ohio (27 counties), Michigan (12 counties), Mississippi (3 counties), Louisiana (3 counties), Washington (1 county), Pennsylvania (1 county), Oklahoma (1 county), Kentucky (1 county), Delaware (1 county), and California (1 county).
Adding the next 297 largest counties in terms of production yields 90% of total production. Most of these counties still are in the Corn-belt. Additional states not listed above with counties contributing to 90% of total U.S. production include North Carolina and New York.
As one would expect, most of the U.S. corn is produced in and on the periphery of the Corn-belt. Other area contributing sizable amounts to total production include the western Great Plains (western Nebraska, western Kansas, eastern Colorado and the panhandles of Oklahoma and Texas) and the Mississippi River Delta (Mississippi, Louisiana, and Arkansas).
Soybean production has about the same concentration as corn. To arrive at 50% of total U.S. production it takes 256 counties for soybeans, compared to 220 counties for corn. To arrive at 75% of total U.S. production, it takes 486 counties for soybeans, compared to 456 for corn. To arrive at 90% of total U.S. production, it takes 743 counties for soybeans, compared 753 counties for corn.
The soybean production region has similarities to corn (see Figure 2). Most of U.S. production can be accounted for beginning in the upper Midwest (North Dakota and Minnesota), coming through the Corn-belt and periphery states (South Dakota, Wisconsin, Iowa, Missouri, Illinois, Indiana, Michigan, and Ohio), and down the Mississippi River (Missouri, Kentucky, Arkansas, Tennessee, Mississippi, and Louisiana). Compared to corn, more soybean production occurs around the Mississippi River and less in the western Great Plains.
Both corn and soybean production is relatively concentrated in the Corn-belt, upper Midwest, parts of the Great Plains and the Mississippi River Region. In some senses, the relatively small region that accounts for most of the production may be surprising. Obviously, production changes in these regions will have large impacts on total U.S. production.