No; I'm from South America. In fact I was mentally comparing MX+USA with the situation here, it depends a lot on the specific region but usually there's a plurality of staple carbs (wheat, rice, potato, corn, yucca...). Cattle food, sugar and renewable fuel are taken up by other crops (soy and sugar cane).

>I would bet those don’t even form a plurality of starchy carb sources in the American diet

That's good. I was mildly concerned about the situation because others mentioned corn farms subsidised by the government - relying too much on them for food would be risky, in the case of a plague.