“Oh, how I wish I had the power to describe the wonderful country as I saw it then!”

So wrote Texas Ranger James Gillett. He kept the peace in 1880s El Paso, ranched near Alpine. “For one who loved nature and God's own creation,” he wrote, “all of western Texas... was a paradise on earth.”

No part of that “wonderful country” has changed as dramatically as El Paso. From a valley of farms and Spanish missions, its metropolitan area now has a million people.

But undeveloped mountains, thorny arroyos and agricultural rhythms remain. The Frontera Land Alliance, an El Paso nonprofit, is working to preserve those pockets of open space.

On El Paso's west side, the Wakeem/...