Intersting article....I grew up in Minnesota and I had relatives in Neb....I never heard about these dunes.
I read about some ancient dunes in Australia, similar situation as this, and the researcher said the only way the dunes could have formed is from a continuous 200 mph wind. (?)
I personally rank them among the most beautiful places I've ever been.
You are probably a youngster and missed "Operation Haylift"
http://movies2.nytimes.com/gst/movies/movie.html?v_id=36540
Nebraska had a bunch of snow in the winter of 1948 - 49 (mostly 49 out west)and many cattle were starving. Hay delivery by plane was a big story in the media. As I recall, the Berlin Airlift was going on at the same time.