A couple of things I learned recently that you might find interesting.
The American distilleries have their own sources for corn, some buying direct from farmers, others from silos. While some of the corn is grown in Kentucky, most of it is from Indiana.
The rye mostly comes from the Dakotas, Minnesota, or Canada.
The wheat used mostly comes from Kentucky, usually directly from the farmer.
One silo in Louisville supplies all of the rye for the industry.
The malt comes from Milwaukee. Malt is in short supply right now and the maltsters are allocating supplies.