The term, Great American Desert, was used in the 19th century to describe the western part of the Great Plains east of the Rocky Mountains in North America to about the 100th meridian. This area, now usually referred to as the High Plains, was considred by some to be as far west as agricultural development could extend.
A short explanation of why some referred to this region as the Great American Desert:
"Dodge City, Kansas lies exactly at the intersection of the Arkansas River and the 100th meridian. In the central Great Plains, the meridian roughly marks the western boundary of the normal reach of moist air from the Gulf of Mexico, and the approximate boundary (although some areas do push the boundary slightly farther east) between the semi-arid climate to the west and the humid continental (north of about 37°N) and humid subtropical (south of about 37°N) climates to the east."
Wikipeida
In the late 19th century, before the advent of region-wide irrigation, proponents and opponents of this belief went back and forth on the pros and cons of farming in areas west of the 100th meridian. An interesting article from the March 1879 issue of "The Quarterly Report of the Kansas State Board of Agriculture" illustrates this issue well.
We've extracted this article from 140 years ago for your reading pleasure here within the virtual walls of the State Library of Kansas' KGI Online Library. Pull up an easy chair, (Please wipe the snow and/or dirt off your boots before you rest your feet on the ottoman!), and read this short treatise on climate and agriculture during a time when settlers were pressing ever westward across the continent.