[VanShuyten]

What we call “The Great Plains”, that land between the Missouri River and the Rockies, was originally called “The Great American Desert” by early explorers and settlers. It was only after exploitation of the Ogallala aquifer that that area became reliable farmland.
A mere 6,000 years ago, Nebraska was dry enough to allow formation of huge sand dunes, and the 300 foot tall Loess Hills of western Iowa were built of wind-blown soil from from vegetation-free lands to the west.

[muawiyah]

There was vegetation near rivers, streams and natural lakes and left over iceage potholes, which meant that in between the great droughts there was always a source of plant life and animals to replenish the desert as the rains returned.

Remember, the earliest American settlers had in their hot little hands maps prepared by even earlier Spanish and Swedish surveyors and explorers ~ then widely distributed through the magic of printing! I've found several townsites in that territory that were undoubtedly laid out according to the Spanish "Law of the Indies" so they were there even if we didn't recognize what they left behind.

[lepton]

“A mere 6,000 years ago, Nebraska was dry enough to allow formation of huge sand dunes”

Some have been dated to 600-800 years ago, and hold data that shows that the predominant wind direction in the area was different than it is now.