Turn right at the stop. If you're in the creek, you missed it.“In early spring 2008, two young bison bulls jumped a sagging three-string barbed wire fence separating Chihuahua, Mexico, from New Mexico in the United States. On both sides of the international line lay an unbroken grassland valley scoured almost bare by a prolonged drought, which announced itself meanly on the dusty hides stretched taught [sic] over bison bones. … Here is a landscape that has seen the birth of jaguars, the death of Spanish missionaries, the budding of Saguaro cactus, the persecution and dogged endurance of native peoples, and the footsteps of a million migrants recorded in the smoldering sands of the Devil’s Road.”

One of the principles I have offered my children and grandchildren has been that books have the power to take us places we might otherwise never visit. One such book is Krista Schlyer’s “Continental Divide.” In words and pictures gathered over several years, Schlyer, a Washington, D.C.-based environmental photographer and writer, takes us to this nation’s border with Mexico, and “The Wall.”

The Wall candidate Trump promises Mexico would pay for. The Wall President Trump now threatens to shut down government if Congress does not take from U.S. taxpayers the estimated $21.6 billion (some estimates run as high as $70 billion) to erect the 2,000-mile-long structure. The Wall that is supposed to keep Mexicans from entering this country without required paperwork.

The 700 miles already constructed seems effective only at blocking the necessary migration of the area’s wildlife.

“A person can climb over the fence in about 15 to 20 seconds,” Schlyer wrote, “but many animals are blocked, which is significant because prolonged droughts are already occurring and expected to get worse with climate change.”

Many wild species, ill-equipped to climb The Wall, will find their water-seeking migration blocked. Meanwhile, as long as there are crops to pick to stock the shelves at U.S. grocery stores, Central American pickers will continue to zip over the wall like high hurdlers in an Olympic contest.

Along the Rio Grande, dams and industrial land clearing between the early 1900s and the turn of the 21st Century has decimated the earth. Now, conservation efforts require tax-funded labor to imitate the former alternating flows of the river, and recover, at least in part, some of the habitat and creatures that once lived there.

Always, it’s the water, as the desert dries what little of the life-giving fluid it held, animals such as Bighorn sheep must find their way to the Tinajas Altas Mountains in southwestern Arizona.

“Luckily for him,” Schlyer writes, “the map he carries in his head of the location of water … has no markings of international boundaries; the only laws he obeys are the life-and-death laws of nature.”

The Wall will imprint his remembered map, as it will for the thousands of human residents whose land it will sever, destroying farmland held for generations, and adding to the cost of The Wall.

“Continental Divide” is a story of an area of division, but also an image of connections – between species, land regions, history and peoples. Like a place we love to visit and explore, every time I reread a page, I find something I didn’t notice the last time through.

At least some of the wildlife could adjust to the disturbance, moving, at least by diurnal cycles, between their natural home in the south and water in the north. Until The Wall.

“Continental Divide: Wildlife, People, and the Border Wall” – the story of what we will destroy, if we build The Wall – is published by Texas A&M University Press, and available in bookstores and online.