Preservationists say that many of the sensitivities that the BLM exercised in energy booms past have gone by the boards. For instance, it allowed the placement of a methane well at the entrance to the magnificent ruins of New Mexico's Aztec National Monument, and it leased land for gas wells near the state's Chaco Culture National Historical Park.

Nonetheless, some companies say they're doing all they can to tread lightly. When Questar, a Salt Lake City energy company that operates in Nine Mile Canyon, needed a new pipeline, it carefully considered its placement, says spokesman Steve Chapman. "There's no way we could avoid Nine Mile," Chapman says. "We reached out to the Utah Rock Art Association and the Nine Mile Canyon Coalition and made it clear that we were doing what we could. We tweaked the route to take into account their concerns." Critics claim that while the BLM's "flag and avoid" mentality might protect a particular site, it misses the big picture—the entire landscape in which history happened—which, by law, must be taken into account. In Wyoming, for example, the dirt trails used by nineteenth-century pioneers headed to the gold fields cross a landscape pockmarked by massive methane ponds and studded with oil and gas wells.

Wyoming may have the distinction of being the most industrialized of the Western states. Most of the activity is in the 13-million-acre Powder River Basin, in the center of the state. The BLM's final environmental assessment says that there are about 24,000 coal bed methane wells here and predicts that the total will eventually reach 56,000—along with thousands of miles of road and pipeline.

"The change is so profound that it's hard to describe," says Jill Morrison, a staffer with the Powder River Resource Council, a coalition of ranchers and environmentalists in Sheridan. "It's the industrialization of what was once largely pristine ranch country. Some days, I want to quit my job and go enjoy the wild areas because they aren't going to be around very long."

Jonah Field, an oil-rich area in western Wyoming, near the town of Pinedale, is at the southern end of the Greater Yellowstone Ecosystem. Each fall, when the snow starts to bury Grand Teton National Park, pronghorn descend from the mountains and travel more than 300 miles south to a broad mesa, where life is made easier by winds that scour snow off the grasses. The graceful white-bottomed animals have used this route for at least 7,000 years, archaeological records show. It's a difficult yet critical journey: If the pronghorn leave too late, they can starve to death, trapped in the deep snow that chokes the passes. The annual migration is their only means of finding the food they need for survival through the winter. Come April, they'll make the trip in reverse.

There are four places where the migration corridor narrows to just a few hundred yards, and one of those bottlenecks was recently converted from open prairie to an intensively developed natural gas field, with roads, drill sites, and other industrial development. At night, the dark rural sky here lights up with the yellow flames of flaring gas wells.