I recently walked across Arizona's Navajo Bridge, 500 feet above the swirling Colorado River.  The bridge was finished 82 years ago -- an epic accomplishment -- and it is now listed as a National Historic Civil Engineering Landmark. I began my walk on the Navajo Reservation, where I surveyed a canyon that was almost destroyed by proposed dams in the 1960s.

The professional beavers at the Bureau of Reclamation had wanted to dam Marble Canyon, but the public said no -- especially after Sierra Club Executive Director David Brower launched a media campaign in the New York Times. Brower's full-page ads featured the memorable slogan: "Should we also flood the Sistine Chapel, so tourists can get nearer the ceiling?

Today, the historic bridge holds no traces of environmental controversy; instead, it honors the historic river crossing and all the boaters who died in the river's rapids. On the Navajo side, the Gap Bodway Chapter House remembers John Deering or Bih Bitoodini Nez of the Maii Deeshgiizhini Clan who transported supplies and mail from Flagstaff to Salt Lake City by team and wagon, hunted the area, and raised livestock.

Another bronze plaque recalls Lewis Nez, born of the To'DiChi'l'Nii or Bitter Water Clan, who hauled freight and mail between Kanab, Utah, and Flagstaff, Ariz. "A friend to everyone," he died with two other men on June 7, 1928, when the ferry overturned into the Colorado. His body was never recovered. That tragic accident, the last one for the ferry, spurred the push for a bridge.

Made of Kansas City structural steel and 500 cubic yards of concrete, the 834-foot-long, 18-foot-wide bridge has a magnificent cantilevered arch. Construction crews dangled 500 feet over the river, building the bridge in two sections -- working outward from each side of the canyon until they finally connected it in the middle. When Navajo Bridge officially opened on January 12, 1929, the Flagstaff paper proclaimed it "the biggest news in Southwest history."

Between 1938-1941, the Civilian Conservation Corps built a rustic stone wayside observation shelter on the northwest side. Plaques commemorate pioneers and early river runners, including boatman Norman D. Nevills and his wife, who began modern river-running on the San Juan. A bronze plaque states, "They run the rivers of eternity."

I admired the craftsmanship of the CCC boys who built the observation shelter and was touched by the commemorative plaques, but it was something under the adjacent 1994 highway bridge that really caught my eye. Walking across the historic span and looking over to the new bridge, I saw what looked like a black plastic garbage bag.

Then I thought to myself, "That's not a garbage bag -- that's one helluva big raven." And suddenly I realized that it was not a raven: It was an endangered California condor, the bird with the 10-foot wingspan. It was hunkered down on a cold girder, looking like a punk rock star in need of a latte.

It was Condor No. 69, according to the tag attached to its wing. The condor's head was fluffy, its neck was red and it looked generally unhappy. It was an overcast morning and the bird clearly needed half a toasted mastodon, just like back in the good old days during the Pleistocene, when condors swooped down on the leftovers after Paleo-Indians finished feasting. But that had been ice ages ago, long before this bridge was built. And here I was staring at the largest bird in North America, back from the brink of extinction.

Then I saw the others. No. 76 sat on a stone ledge where the bridge connected to the canyon, and a third bird, perhaps No. 54, stayed in seclusion against the rocks. My wife and I watched them for nearly half an hour as they used sharp beaks to preen their feathers. Then they took off quickly, becoming tiny black eyebrows flying away against the immensity of the Grand Canyon.

Navajo Bridge is an engineering marvel, and its construction united southern and northern Arizona. Still, too much of the American West in the 20th century was about building, changing and manipulating the environment solely for human benefit. We showed that we were learning restraint when we stopped needless dams in Marble Canyon, and yet our real accomplishment may have been passing the Endangered Species Act of 1973, which puts humanity in its place as a member of the vast community of life.

I respect the bridge's bronze memorials, but I treasure even more the living wonder of California condors once again flying above their ancient turf.

Andrew Gulliford is a contributor to Writers on the Range, a service of High Country News (hcn.org). He is professor of Southwest Studies and History at Fort Lewis College in Durango, Colorado.