The Great Plains by Historian Walter Prescott Webb
In his masterful work, The Great Plains, historian and long-time University of Texas professor Walter Prescott Webb states: “East of the Mississippi civilization stood on three legs—land, water, and timber; west of the Mississippi, not one but two of these legs were withdrawn—water and timber—and civilization was left on one leg—land.”
The Line of Semi-Aridity
Walter Prescott Webb identified the 98° of longitude as a climatological and, eventually, cultural fault line where ways of doing things had to change significantly for settlers to make a life under vastly different circumstances. This invisible but very real border boundary was the line of semi-aridity.
East of the Line of Semi-Aridity
East of the line, institutions and ways of life remained consistent with those stretching all the way back to the Atlantic seaboard. Anyone moving from East to West would certainly have faced daunting challenges that had to be overcome in order to prosper.
West of the Line of Semi-Aridity
West of that line, the means of travel, the methods of tilling the soil, the techniques for ranching, and the tools for survival changed.