I just drove through Montana on Highway 2 and US 94. Montana has never looked so lush and green in the middle of July. Every section of land seemed to be growing nicely with wheat.
Like North Dakota, Eastern Montana highways follow paths of least resistance--the smoothest track. We've had a lot of rain this year, the grass is green six weeks after it usually turns borwn.
There are vast areas of North Dakota and Montana north of the interstate which are too rocky (glacial moraine) or too steep (badlands topography), or are otherwise unsuitable for farming wheat, but make good grazing land.
Vast BLM owned tracts are grazed as well, but farming is out.
If the land will make a good living for those farming it, it is generally being farmed unless the government has put the skids to that.
Corn, BTW, is a relatively uncommon crop here. Between wind loads and water requirements, it doesn't generally do well outside the river bottoms.
See also Hodar’s post #35. Part of the problem was that you drove on I-94 and US 2. These are, even by Montana standards, excellent roads. They also have nearly parallel railroads which drastically lower the cost of shipping grains. Try going up into the nethermost regions Missouri Breaks or isolated little towns where the roads are poor and there are no railroads. Growing grain in these areas, while it might be possible, is seldom profitable. Yes, a rancher may grow enough grain to help his cattle through the winter, but many of the few towns you see won’t even have grain elevators. Why do you suppose that is?