From a small plane flying only 1,500 feet above the Arizona desert on a hazy February day, the landscape appears as beautiful as it is inhospitable. The sandy dirt glows in psychedelic orange and yellow, and the little mountain ranges southwest of Tucson look like bristly cactus transformed into stone, thrusting upward to nearly touch the plane. There are few signs of human activity until we approach the Mexican border, where Organ Pipe Cactus National Monument and Cabeza Prieta National Wildlife Refuge, two huge conservation areas, supposedly protect more than a million acres of federally designated wilderness.

"There's one," Cyndi Tuell, a conservationist lawyer, explains over the headset. She has her long reddish hair rubber-banded into pigtails, and her forearm tattoo commemorates Rachel Carson's courageous 1960s Silent Spring broadside against pesticides. Pointing out her window, she adds, "And another one – do you see it?" Quickly the number grows: "Five, six ... 10, 12 ... This really pisses me off. It's worse than I thought."

Tuell is counting "renegade roads" – the vehicle tracks shooting off in all directions from the few legal roads. At least 10,000 miles of renegade roads have been carved into the wilderness areas that make up more than 90 percent of the total area of the monument and refuge – even though wilderness is, by law, supposed to be "untrammeled by man." It's probably the worst violation ever of the spirit of the 50-year-old Wilderness Act.

Even more surprising: Though smugglers and undocumented immigrants sneaking north from Mexico began creating renegade roads decades ago, these days most of them are made by U.S. Border Patrol agents trying to seal off the border. Below us, Border Patrol trucks and ATVs cut across the desert, generating a plume of dust. "A lot of these renegade roads are new," Tuell says. "Every time I fly here, I see more new ones."

Skittish desert bighorn sheep live in these wilderness areas, along with rare Sonoran pronghorn, desert tortoise and unnervingly large blond tarantulas. All of the local wildlife is stressed by the surge in Border Patrol traffic, which continues to bring noise, erosion and human presence to a once-remote corner of the West. Our pilot, Will Worthington – a gray-haired, semi-retired engineer with Lighthawk, a nonprofit conservationist flight service – circles the plane into Mexican air space and back, so we can see how the U.S. government has also fortified this border segment with walls and fences. The barriers further fragment wildlife habitat. Yet few people know about it, partly because most environmental groups shy away from the issue, wary of tangling with national security and immigration politics.

The handful of environmentalists who are involved – like Tuell, who is volunteering her time – can't even use their standard tool, litigation, because Congress has decided that environmental laws do not apply along the U.S.-Mexico border. It's a lopsided battle, fighting the militarized Border Patrol and the politicians who exploit anxiety over national security, and at times, Tuell says, "It seems hopeless." To me, the spiraling tire tracks on the Arizona desert resemble the ancient symbols inscribed into the deserts of Peru and Chile by people of the Nazca culture, more than a thousand years ago. The Nazca likely created their giant geometric shapes for religious purposes. But these Border Patrol designs, which will also persist for a long time, symbolize something darker: our 21st century fear and anger, and a burst of U.S. government lawlessness.