That whole region had ridiculous yields for years after Mt. St. Helens blew (it was in the ash plume -- great fertilizer) but they had difficulty moving that volume economically during years when the rest of the country had high yields. Or at least that is my recollection as a kid. Once they started dumping grain, the pile only got bigger.
Some of the piles in Indiana and Kansas would make you think they are building a ski slope. First time I saw one I was so confused given that moisture is such a problem and drying is not cheap. Some elevators make a lot of profit managing moisture.
 If you are an awesome engineer and can figure out a cheap way to dry grain / corn, there is one big market for you.