A little mining town, surrounded by the sagebrush and hills of western dryland, quietly lives out its story of boom-and-bust and modest comfort until one day the U.S. Air Force comes along with a plan called MX missile bases.

The MX missile complex is not just another military installation that the Pentagon wants to build in the barren valleys outside Tonopah. It is one of the largest public works projects in American history -- right up there with the transcontinental railroad, the interstate highways, even the Panama Canal. While it lacks the grandeur of those efforts, the MX surpasses them in complexity.

Ten thousand miles of roads, 2,000 miles of railroad tracks, gargantuan vehicles toting intercontinental rockets around 200 desert tracks -- all this and more will be built in the deserted valleys of central Nevada and Utah, assuming everyone approves.

Local feelings, as one might expect, are mixed.

"I'd make some money off the damn thing," said Danny Robb, president of Tonopah's Rotary Club and a fifth-generation resident of this town of 3,000. "But I'd like to see the MX go someplace else . . . We've already got all the lifestyle we need."

But Eddie Peddie, a former comic and now manager of the Mizpah Hotel, cannot wait for the concrete to pour. He has been trying to put some fizz back into this town, which bubbled with prosperity 79 years ago when Jim Butler struck gold and silver. The Mizpah has a spotlight on its roof which at night illuminates a huge white "T" on a nearby hillside.

"This town is going to bust wide open," Peddie said gleefully.

David Hamilton, Nye County planner and, like Peddie, a non-native, thinks the desert can handle MX, too -- if the vast and complicated development is done carefully.

"Judicious expansion is not considered bad," as Hamilton carefully put it on behalf of the county commissioners.

The Rotary president is still skeptical. "What more are we going to get from the MX?" Robb asked himself. "A golf course? It might be all right if they brought in 15,000 very good people . . . but I haven't seen that military and government operations bring in the cream of the crop."

Brig. Gen. Guy Hecker is the point man for the Air Force sales pitch, which must convince citizens and politicians of Nevada and Utah that MX will be good for them, even as it defends America against nuclear attack. A soft-spoken native of Alabama, Hecker speaks in a language these western descendants of prospectors can understand.

"I have a good feeling," the general began, "every time I cross the 100th meridian coming west."

Hecker was before the weekly luncheon of the Rotary Club, warming up his audience for the strategic intricacies of MX with a little down-home talk about the American West.

"I've grown to love and admire the people out here," he said. "To me this has really become Heartland America -- independent spirit, patriotic spirit -- just the things you all stand for. I wish we could get all of the bureaucrats out of Washington and out here to see what the real America is all about. I really mean that."

Applause from the Rotarians of Tonopah.

The lights were dimmed and the general began his grim exposition of the Soviet threat, depicted on the slide screen. One slide showed a black pendulum of nuclear superiority, swinging away from America and toward the Soviet Union. He took the audience through the complicated comparisons, giant Soviet missiles versus smaller American ones, the multiplication of Soviet warheads, the vast number of rockets aimed at the United States.

"You have to start thinking of what would happen should [there be] -- and God forbid if it ever does -- 6,000 simultaneous explosions of one megaton over the entire United States."

The MX is the answer and the general spelled out the strategic thinking -- a giant shell game with U.S. missiles -- that created this staggeringly complicated project. Then he spelled out how complicated it is.

The plan calls for about 200 MX missiles, each carried on a giant truck. Total weight: 335 tons. Cost for just one truck, $4.7 million. Cost for the whole MX complex, $33 billion.

Each MX and its truck will be assigned to a desert track, an oval loop of 20 miles or so, and each track will have 23 garages where the rockets will be parked temporarily. They will be moved periodically, to keep the Soviets guessing. This maze will require thousands of miles of railroad spur lines and access roads, both to get the rockets into the desert valleys and to connect the 200 different loops where the missiles will be hidden.

The MX missile is directly linked to the debate over the strategic arms limitation treaty (SALT II). The mobile, hard-to-hit MX, President Carter and his SALT II allies are stressing, will ensure that U.S. land missiles could not be knocked out in a surprise attack by the big Soviet missiles allowed under the treaty.

The Rotarians were told by the general that this is "man's largest project." The MX construction, for instance, will cost nearly three times what the Alaskan pipeline cost. It will bring 25,000 construction workers to their desert and they will need 30,000 workers in support -- everything from housing to recreation. The general did not need to mention that in Tonopah, Nev., prostitution and gambling are legal.

After all the concrete is set and the rockets are in place, the complex will require about 14,000 persons as permanent operators. Hecker estimates $400 million a year in federal paychecks plus $1 billion in federal aid for the "multiplier effect" of large government undertakings.

The general acknowledged that central Nevada's lifestyle is in for change, but he emphasized the big pluses. MX electricity will come from solar, wind and geothermal sources -- perhaps the world's largest demonstration project for these alternative energy sources.

MX will create a generation of new careers for Nevada's young people -- high technology jobs in an area where tourism, mining, entertainment and cattle grazing are dominant.

While the Air Force's 200 loops of missile tracks will eat up a lot of ground, Hecker promised that the general terrain and the new roads will be open to the public, both for camping and for cows. Only the 2 1/2 acres required for each of the 4,600 rocket garages will be fenced off.

In conclusion, the general offered a gentle warning that, if Tonopah and Nevada do not want MX, there are other places that do.

"Governor Herschler of Wyoming called me personally," the general advised. "First time I've ever picked up the phone and heard, 'I'm Ed Herschler, the governor.' To express his interest in getting the MX in his state,"

Other states are interested too, if Nevada and Utah prove resistant, Hecker said.

"There are a couple of other governors who've said, 'If you get a hiccup, the door is open.'"

Like citizens of Tonopah, politicians of Utah and Nevada have mixed feelings about this great federal project for the vacant rangelands. Rep. Jim Santini (D-Nev.) took his worries to the floor of the House earlier this month.

"Twenty-two thousand to 30,000 proposed employes for a period of approximately five years will impact an area which now has only about 7,000 people," Santini said. "Where is the water coming from? What are the socioeconomic impacts? No one is in a position to respond to that concern today either within the military establishment or without."

Santini asked the House to insure that no state will be required to take more than 25 percent of the missile complex. Nevada, under present plans, will have to handle about 65 percent of it.

The rebuttal came from House Armed Services Committee leaders who read a letter from Nevada's Gov. Robert List, a Republican, welcoming MX into the state. The House turned down, 289 to 84, Santini's effort to spread the MX work around to ease the impact on Nevada.

In the Senate, Nevada Democrat Howard W. Cannon and Republican Paul Laxalt are slightly out of step on the MX. Cannon has said that planing can "greatly reduce any adverse effect" of MX, adding that the 14,000 permanent employes required to operate the system will insure against a "boom to bust" pattern.

But Laxalt said "unanswered geographic, economic and environmental questions are responsible for my reservations about putting the MX in Nevada. Besides, MX deployment would make my state a nuclear bullseye."

Santini, waging an uphill fight against putting most of MX in his state, persuaded the public lands subcommittee of the House Interior Committee to assess the environmental consequences of the project at a hearing in Carson City.The committee would have to approve the release of government land under the Bureau of Land Management to the Pentagon for MX construction.

Meanwhile, the Carter administration anticipating environmental suits against the MX, is considering the designation of a single federal court to hear all of the lawsuits.

"I'm for the inevitable," said Joaquin G. Johnson, superintendent of schools in Nye County, a school district that covers 18,000 square miles of Nevada.

After hearing Hecker, Johnson can visualize thousands of children of MX workers pouring into his schools. "But we'll be helpless unless we get some help," he said.

Rancher Wayne Hage, who runs 2,000 cows outside Tonopah and is an officer of the Nevada Cattleman's Association, said his group will insist that any land removed from grazing for the MX be replaced by other lands suitable for cattle. This might require planting wheat and digging wells on land given to ranchers in the swap.

Even if this is worked out, said Hage, the MX will bring "a drastic change in the economy of Nevada, replacing the currently stable one of producing renewable resources." He means beef cattle.

Nevada state Sen. Richard E. Blakemore, who runs a trucking business in Tonopah and is an officer in the western states' pressure group called Sagebrush Rebellion, said the MX can do wonders for the state. He scoffs at environmentalists and their approach to nature.

"They say they want to lock this land up for all the people," Blakemore said. "But who the hell are all the people? Bull -- .It's not for all the people, only for that segment physically able to use it."

Blakemore, given a choice, would rather see Air Force missile tracks than barren emptiness reserved for wilderness hikers.