If you examine any good map of Texas, you will notice a natural division of East and West Texas that runs from the eastern side of the Panhandle down to Abilene and San Angelo and on past Uvalde to Carrizo Springs and Laredo.
On the west side of that line is arid land and on the east side it is wetter and greener land. And it becomes increasingly dry as you go west and increasingly wet and humid as you go east.
This line is better known as the 100th Meridian and it maintains this calculus of wet and dry lands all the way up into Canada. The 100th Meridian is a natural border one can see clearly on the map bifurcating America as well as Texas.
John Wesley Powell, famous for exploring and mapping the Colorado River and the Grand Canyon 150 years ago, was one of the first conservationists to see that the 100th meridian served as a demarcation of America’s greener east and dryer west.
He wrote:
“Passing from east to west across this belt a wonderful transformation is observed. On the east a luxuriant growth of grass is seen, and the gaudy flowers… make the prairie landscape beautiful. Passing westward, species after species of luxuriant grass and brilliant flowering plants disappear; the ground gradually becomes naked, with bunch grasses here and there; now and then a thorny cactus is seen, and the yucca plant thrusts out its sharp bayonets.”
Wallace Stegner wrote that land west of the 100th Meridian was “treeless except for… cottonwoods along water, deserted except for coyotes, and an occasional shanty, and the ungathered bones of the buffalo. [It was] domed over by a great bowl sky… at whose western edge the sun set in clear distances of lavender and saffron.”
Powell, for whom Lake Powell is named, would become the head of the U.S. Geological Survey in 1881. He used his enormous personal knowledge of the west to create a prescriptive map for water management of the arid half of the U.S. It was an objectively beautiful map, as ahead of its time in persuasive visualization as it was in its policy proposals.

Torpyl, CC BY-SA 4.0 via Wikimedia Commons
Powell took his map to a senate committee and suggested dividing the western U.S. into water districts that would be managed by the people living along the rivers rather than the states.
For instance, he envisioned the Pecos River of New Mexico and Texas being managed by farmers and communities that lived along the banks of that river. And he suggested that land not be divided into neat rectangles, but rather in whatever shapes were needed to make sure all the farms had access to water. He advocated for need over greed.
The senators practically rioted as this flew in the face of the fever dream of Darwinian development that had dominated the western states for decades. The gold must be mined, the forests harvested, the rivers dammed, and the railroads built by the fittest, the smartest and probably the richest.
This was the Gilded Age, after all. Land development was not to be governed by water. “Rain follows the plow” was the unscientific mantra of the time. “If you plow it, rain will come.”
John F. Ross, writing for The Smithsonian noted that “Powell’s map forced the viewer to imagine the West as defined by water and its natural movement.” Powell’s map argued for sustainability and good stewardship of the earth. He was against big dams – ironically, given that his namesake lake was created by Glen Canyon Dam. He preferred smaller, more democratic irrigation systems that he believed would be more efficient for the land and serve more people, more equitably.
As we know, the arid west was not developed as Powell envisioned, but it is interesting to consider what might have been if Powell had had his way. West Texas might lean toward what he had in mind civically, many smaller towns and cities sparsely distributed.
What’s more interesting to me at this moment are the facts on the ground in Texas these days. The geological truths that defined the 100th meridian in Texas a century and a half ago, are now truer for the 98th meridian, running just west of Fort Worth, east of Austin, and east of San Antonio to Corpus.
This tells us that the Texas water challenges of the future will be far greater than any our ancestors faced.