her yellow four-wheel-drive Chevy and rattles across the desert to the Coyote Butte quadrangle, an hour west of town. She will do supplemental control work—obtaining elevations and positions for points scattered throughout a quadrangle—from a nameless hill 3,346 feet above sea level. The hill, a pile of black volcanic rubble sticking out of the brown Idaho prairie, happens to be in the middle of the Idaho Army National Guard Firing Range, and a bullet-riddled sign at the entrance warns visitors not to pick up unexploded ammunition. As artillery rumbles around her, Jamie peers through a T-2 theodolite at another theodolite set up by Abe Trimble several miles away.

Abe Trimble and Joe Sadlik are criss-crossing Coyote Butte in their own pickups, setting up controls and getting elevations. Dust devils twist and writhe across the plains, and snow-patched mountains are visible far to the south. Army helicopters thump by; Coyote Butte itself, which Jamie has not been able to pick out until Abe signals by mirror from its summit, turns out to be a disappointing jumble of rocks seven miles away.

“ That little thing?” Jamie asks Abe over the radio. “I thought it would be a lot bigger.”

“I guess you have to be here to appreciate it,” says Abe.

Abe’s signal light looks like a flicker of brush fire through the hazy magnification of the T-2 scope. A theodolite is an instrument that—underneath the complicated optics and two-thousand-dollar price tag—essentially measures angles. If you point it from a hilltop to another location, it will tell you exactly what angle it must tilt at in order to see that spot. Then you take an instrument called a Microfix, which bounces microwaves off other Microfixes, to learn almost to the inch the distance between the two locations. Since you always work from a position of known elevation—called the turning point—simple geometry will calculate the elevation of the other point. Slowly, control after control, quadrangle after quadrangle, the U.S.G.S. has put together the fifty-five thousand maps that make up its 7½-minute-scale portrait of the United States.

According to Jamie’s instruments, Coyote Butte is 37,797.4 feet away and 30 minutes and 6.5 seconds below horizontal. Later, in the Denver office, others will determine whether these elevations are accurate enough to be retained on the map. They’ve got such good mathematics, they don’t even need to test elevations in the field anymore,” Jamie says. “You give them one fixed elevation and they send it through aero-triangulation and they can get 20 more elevations off that one. It’s pretty expensive to be out here, and so we don’t do this very much.”

The official dream of the main U.S.G.S. office, in Reston, Virginia, is that geographical data for the entire country will eventually be stored digitally. Buying a map will entail specifying not just the quadrangle but also what you want on it: latitude and longitude, contour lines, mineral rights. The computer will then print your tailor-made map

while you wait. Many maps will be updated not by field workers but by office workers studying satellite photographs—”photographs so accurate,” Jamie says, “that they have identified the plumbing in a burnt-down house.” Such photographs are also used for spying, and to work with them requires a security clearance. Jamie has applied for a clearance, but the FBI is stumped; she has moved around so much in her life that they can’t find anyone who knows her. They finally had to call her for help.

When a cartographer does go into the field in the future, the control work may not be done by T-2 theodolite but by something called GPS: global positioning systems. Orbiting satellites will tell you exactly where and at what elevation you are at any moment.

“They say they’re going to phase us field workers out,” James says, “but they say a lot of things.”

What amounts to a catastrophe of technology for field workers should occur in some form within the next four years. It’s perfectly plausible now on paper, but there are problems yet to be resolved. How, for example, do you enter all that data digitally? The amount of information in a single map is huge, and the amount represented by the entire country is virtually unthinkable. Entering it could take years.

The area of cartography perhaps least vulnerable to change is called field completion or revision. Features that are hard to distinguish on a photo must be identified in person. Even a spy photo would not show a dirt road beneath dense tree cover. Field workers must go out and check these details. “Even people in the office don’t know how much work goes into these maps,” says Phil Ibarra. “It takes four to six weeks for a field worker to complete one quad.”

Ibarra is lurching through the rugged hills south of Glenns Ferry, Idaho, in a four-wheel-drive truck. On his lap is an infrared photo of the area that he glances down at from time to time, keeping track of his position. The truck rises and falls over the prairie like a ship at sea. “Right now I’m checking to see if a dirt road from the old map is still drivable,” he says.

It’s not. The truck, an unstoppable-looking beast painted government white, cannot squeeze through a particularly narrow draw. Surveyors have rolled trucks into rivers and nearly driven off cliffs during field completion. One field worker had to walk seventeen miles on an injured leg to get help. Another lost a truck in a flash flood; yet another is famous for setting a stretch of rangeland on fire with an overheated catalytic converter. Still, very few U.S.G.S. cartographers have ever died in the field—or even been bitten by a snake.

Phil is dressed in a bright yellow shirt and a blaze-orange vest. He has been in the field for 15 years and is loath to leave. “I have crossed

every meridian on earth,” he says. “A lot of people don’t like places like this, because it’s just sagebrush. I like it because you’re alone and no one bothers you. It’s a lot of nothing out here.”

Probably the most nothing a person could experience is Antarctica, and Phil has been there twice (he has a T-shirt that says, “Ski the South Pole: 2 miles of base, a ½ inch of powder”). Apparently the exact South Pole moves continuously—that is, nine-thousand-foot-thick ice drifts over it—and the United States periodically sends expeditions to relocate the markers. Phil was on one such expedition; another time he was part of a joint U.S.-New Zealand team that established controls for an area called the Dry Valleys.

For the time being, Phil’s job isn’t quite so exotic; he’s simply driving around the Deadman Flat quadrangle with an infrared aerial photo, checking for what he calls “culture.” Culture is anything man-made: houses, gas pipelines, fence scars. Culture includes the Oregon Trail, a century-and-a-half-year-old rut in the prairie that happens to cross the farm road Phil is on. It winds along a dry wash and then over the crest of a hill; the immigrant who bumped over these rocks had another four hundred miles to go before reaching the Promised Land of the coast.

“I’ve worked on projects with the pony-express route too,” Phil says. “And I was at Wounded Knee after the Indians shot the FBI guy. Talk about tense. Another time we were warned away from the Mexican border because of all the drug trafficking. Maybe the most difficult state to work is Texas. You have to ask permission to cross someone’s land, and most of the people who say no live in Texas. They’re real paranoid of the government there.”

Two of the very last quads in the country to be mapped at 7½-minute scale are just south of Mountain Home in Elko, Nevada. Nevada is a rugged place, and it is somehow appropriate that it held out so long against the scrutiny of cartographers. Phil considers Nevada the easiest place in the country to work in; people in such isolation tend to cooperate with one another, he says. Indeed, it’s hard to stop on the highway for a photograph without having someone pull up behind you to ask if you need help.

The man in charge of the projject in Elko is a leathery-skinned veteran named Ben Rush. His temporary headquarters is crammed with the nearly immovable steel office furniture of the 1950s. Scattered over every flat surface are maps, land plats, and aerial photos. One map has hills cross-hatched in an old-fashioned style and is marked “Unsurveyed Lands.” In a corner sits an old wooden box containing an alidade, an instrument for drawing maps while in the field. Rush has been with the

U.S.G.S. all his thirty-five working years. His eyes have squint lines, and he wears khaki issue from his neck to the tops of his shoes.

“Cartographers in the last generation before me would start out in the spring with a string of horses and mules and wouldn’t come back till fall,” he says. “They had a blank sheet of paper and an instrument called a plane table and would stay out all summer making their maps. In those days the men who did the field work had their names published at the bottom of the map.”

Rush saw the early days of the 7½-minute project and now has the satisfaction of putting the very end of it to bed. He says the last great advance in mapping was the introduction of aerial photography in World War H; the next great advance will be the Mark II or “Modernization” program—spy photos taken from satellites. “The powers that be think that they don’t need field workers. Well, I may be a little partial, but in order to do it properly, someone’s going to have to do a little field work. I like to see advances, but I don’t like to see us eliminated.”

One of the tasks facing Rush is updating something called the land net. The land net is a pioneer-era grid of stone and brass markers across much of the West that divide the land into one-mile sections. Some markers that have been destroyed by new roads are called accepted corners and are shown by an X on the new map. They are abstractions, known points that exist only in the minds of the field workers. As such their value is mainly historical, but they also provide a metaphor for the future of the field workers themselves.

September 1991: For more than forty years the U.S.G.S. was absorbed in the monumental task of mapping the entire country at 7½-minute scale. Now the job is done. The field workers I visited two summers back finished their corner of Idaho not long after, and five of them now sit at desks full-time in a U.S.G.S. office in Denver, two permanently and three awaiting future assignments doing revisions in the field. Ben Rush has retired and lives in Nevada; those who have stayed on are preparing to hover over the high-tech cartography of the future like phantom section corners over a new road, the only blank spot on a map they themselves helped draw.