The Plains winters of the early 1970’s were cold; as I recall the winter of 70-71 was also particularly snowy.  However, that did not stop the summers from being hot.

It was July, 1973, temperatures were into triple digits and a dry southwest wind was blowing across the High Plains toward the Great Plains.  I and the old John Deere 55 were just about done-in; the combine was turned so that the wind would blow through the radiator in a mostly-vain attempt at dropping the engine temperature below the red.  I was feeling pretty much the same way.  We had been cutting wheat for most of the week and the high temperatures and low humidities meant that we were running from early morning until deep in the night and getting a very few hours of sleep before going back out again.

While waiting for the 55 to cool down, I happened to look toward the east, across the 10 miles that separated me from the Great Plains and the American MIdwest.  Ten miles into the High Plains and ten miles deep in the American West…what are we doing here?…

The 100th Meridian (100º West Longitude) in the dryland (non-irrigated) wheat country of Kansas is roughly coincident with US 283, running north-south through places like Norton, Ness City, Jetmore and Dodge City. Also roughly coincident with the start of the Oklahoma Panhandle, it is tracked by US 83 up in Nebraska (McCook, Stapleton, Thedford, Valentine) and again down south in Texas (Canadian, Shamrock, Childress, Guthrie).  It is also roughly coincident with the transition from the Great Plains to the High Plains.  If you look carefully you can tell.  The undulating Great Plains to the east, although still grasslands, have a rolling, hummocky morphology and the feel of humidity in the air.  The High Plains, by comparison, have a much flatter aspect, and one that displays a gradual, but continual rise from the 100th Meridian and an elevation of about 2000 feet to the Rocky Mountain front and elevations that can exceed 5000 feet.  The land is not as lush, not as green, but the sky is bigger, the stars at night shine more clearly, and the air carries the feeling of aridity.  Welcome to the 100th Meridian, welcome to the American West.

The 100th Meridian.  The place where a subtle, but distinct physiographic change occurs.  It’s also roughly the line of demarcation for the tall grass prairie found to the east and the short grass prairie found to the west. It is at this point we need to introduce another number, and one that is even more important in understanding the hardships associated with Life on the Edge.  That number is 20.  The 100th Meridian is also roughly (“roughly” being the operative word) coincident with the 20” isohyetal, or the line indicating 20” of annual rainfall.  The line of 20” annual rainfall is sublime, almost magical.  Stay on the high side of it (in other words, in an area that has more than 20” of annual precipitation) and you can build an agrarian society that can stand the test of time, sustainable not for decades but for centuries.  Flip to the other side (an irrigation society = imported water) and find yourself facing a far more problematic history with respect to long-term stability. The line separating the tall grass and short grass prairies is actually the 20” isohyetal.

The Homestead Act of 1862 really kicked off migration into the 100th Meridian country.  The Kincaid Act (1904) brought even more farmers into the perilous landscape of the 20” isohyetal.  The 1910’s and 1920’s were great years for farmers on the Edge.  World War I and its aftermath in Europe created a huge market for American wheat.  There was a 20 year period when the region experienced greater than normal rainfall as the 20” isohyetal shifted to the west. The shortgrass prairie was plowed and millions of acres of dryland wheat put in.

And then there was 1929, with the onset of the Great Depression causing the bottom to fall out for wheat prices.  And then there was 1931, when the 100th Meridian country went into drought (which caused the 20” isohyetal to shift dramatically to the east). The rest, as they say, is history.  The decade-long Dust Bowl was a singular event in US history; the ramifications have reverberated across the country for nearly a century.  It has been chronicled in many ways by more than a few, but Steinbeck’s California novels about the 1930’s are a good starting point with respect to their reflections on the human condition during those years.

It is true that irrigation societies through time and around the globe have had their own issues with long-term sustainability, but as a continuing Pale there is nothing quite like living on the 20” isohyetal.  Here on the 100th Meridian, with the Great Plains on one side and the High Plains on the other, on the line separating the Midwest and the West, at the transition between the tall grass and short grass prairies, the question of how much rain this year takes on a poignancy unlike anywhere else.  100/20: Numbers from the Edge.