The black iron bars went up across the windows of Dean Munkres' combination Conoco station, post office and general store here about two months ago, right after the secord burglary.

Somewhere else - New York City or Los Anglese perhaps - no one would gives bars on the windows a second thought. But here in Bill, with a permanent population of 1 to 35 miles of open rangeland to the next town, the bars are regarded by Munkres as a dark omen of the changes that are sweeping like a praire thunderstorm into this coal-rich state.

The arrival in Wyoing of some of the world's mightiest corporation with their billion-dollar coal development plans has already begun to change the way people do business, not excluding the politicians in the state capital at Cheyenne.

"You can't get in the way of the big boys," said Munkres, an affable man in a summer straw cowbooy hat who is mayor, postmaster, police chief, town spokesman and just about any other title he chooses to confer upon himself at the moment.

The assessment is delievered with a certain amount of dejection on Murnkres' part. Coal developers are making plans to open strip mines all over; a new railroad line to haul the coal is slated to be built through his backyard; an energy company wants to construct a $1 billion coal gasification plant down the road, and recently two good rancher friends were shot and killed in a bar after an argument with a coal company employee.

"This is an altogether different crowd of people moving in here than we're used to," Munkres said. "They're changing things around quite a bit."

There is no doubt that what will come out of the eastern Wyoming coal fields is going to affect the rest of the nation's lifestyle in the coming years. Already, state experts estimate there may be $50 billion worth of coal related development in Wyoming in the next 10 years, including 19 new strip mines and a still-uncertain number of big coal conversion plants scheduled for construction in the coal fields.

In fact, there is so much coal here, the local boast goes, that if Wyomnving's Converse and Campbell counties were to be lopped off the rest of the country, someday they would be the world's fifth-riches coal producers entirely on their own.

But while the impact on the rest of the country is still in the corporate computer models and the heads of President Carter's energy experts, the effect of the nation's coming coal needs is already being felt here in a state that ranks 49th out of 50 in population size.

Some of the charges are subtle: researchs studying the local impact of the coal boom, for example, discovered recently that in some areas the age-old springtime tradition of cooperative fence-mending among corporations, with coal rather than cattle on their minds, purchased ranches for their coal seams below.

And some of the changes are very obvious: the arrival of the coal developers has shifted the deeply entrenched political power structure in the state capital.

For generations politicans could rely on the big Wyoming Stock Growers Association to carry the most political clout in the state and to ally itself with the Union Pacific Railroad - the states other traditional political power - on most matters.

As the struggle for Wyoming's small water reserves grows between the cattlemen and coal developers, however, the stock growers group has joined the state's conservationist faction, a political union that until recently would have been unthinkable.

The Union Pacific, meanwhile which owns large coal-rich tracts in southern Wyoming, has increasingly sided with a former enemy - the unions - on matters involving coal development.

While one-third of the legislature still belongs to the stock growers organization - down from about half a decade ago - the energy companies and coal developers have taken over as the tate's most powerful lobby.

"They're slick," said state Sen. Roger McDaniel, "We've had them in here from New York, Los Angeles, San Francisco, Indiana, Oregon and all over. I suppose to some extent some of them are a little intimidating for a part-time legislator."

Under the state's creaky legislative structure lawmakers meet in 40-day sessions every other year, with a 20-day budget meeting on the intervening year. Pay for a Wyoming legislator is $65 per day while the legislature in the session.

The pressures on legislators can be immense. Texaco, which spent $28 million preparing its property at Lake DeSmet near the Montana border for a coal gasification plant, faced the possibility this year of losing its erucial preferential water rights to local ranchers unless the legislature granted it a five-year extension.

The bill passed and was signed by Gov. Ed Herschler even though Texaco refused to tell state officials what it would be doing with the water.

One legislator sais "a swarm of lobblyists" had appeared supporting the bill.

The presence of high-powered lobbyists from multi-national corporations pushing billion-dollar projects before low-paid, part-time lawmakers working in a state with no financial disclosure laws has raised serious questions among some legislators.

McDaniel, who works for Rep. U.S. Teno Rencalio (D-Wyo.) in the congressmans Cheyenne office, noted that a number of his fellow state legislators either work for energy companies or have their own mineral holdings.

During one important but closed committee session this year two of the six committee members voting on a bill to raise the state coal severance tax had mineral holdings of their own. The committee voted to lower the tax from the level proposed earlier by the legislature.

McDaniel said he had attempted four times during his seven years in the legislature to get a financial disclosure bill passed. The bill was defeated each time.

Herschler, who was a member of the state legislature for 10 years before becoming Wyoming's governor in 1975, in an interview last week that the state's legislative system worked in years past because it was so small.

"Everyone knew everyone else's business and that kept things under control," said the 58-year-old governor. But he added, "Now we're dealing with new people and huge amount of money. I know that somewhere down the road someone's going to get caught with their hand in the till."

Herschler drew some attention recently when a Wyoming newspaper discovered that he and a top Democratic Party official were planning to purchase a 20,000-acre ranch. THe ranch, located in the central part of the state, is in an area where a large amount of oil and uranium prospecting is under way.

A spokesman for the governor said Herschler would decline to comment on the purchase. "The governor views his personal business as just that," the spokesman said.

North of Cheyenne, where the coal is to be mined at the rate of more than 200 million tons per year by 1985, the changes in lifestyle brought on by the coal boom are more personal - like the bars on Munkres' windows.

"It used to be," said James Thompson, a Unversity of Wyoming sociologist, "that there was an informal system of credit in these towns. You could go in and charge things and people would trust you."

The arrival of thousands of outsiders, unknown and somewhat distrusted, has brought a more impersonal formality to the system, said Thompson.

Thompson and a team of sociologists and economists have been studying the effects of the coal boom on the lifestyle of the old ranch towns as the boom takes place. Surprisingly, they have found that, despite some breakdown of the old ways, the overall effect of the coal boom may actually prove beneficial for this region in the long run.

Boom towns are getting schools, health facilities and government attention they might never have received without coal development, said Thompson.

Moreover, he said, the arrival of the coal companies with lots of money and no obligations to tradition is breaking up what the research team fund was an almost feudal system run by a few wealthy and powerful ranchers.

However reassuring that may be to other residents of the Western coal fields, the arrival of the giant energy companies to this part of rural Wyoming is not being hailed by Munkres in his isolated store.

All that it has brought so far, he said, is the departure of some of his long-time rancher drinking companions, a few brief visit from corporate public relations men and a new burglar alarm that rings over the CB radio in his son's pickup truck.

In fact, Munkres said, the coal boom is tempting him to do just what he did when life got to hectic the last time and caused him to move out here to Bill.

"I keep thinking," he said, glancing out through the barred store window, "that what I really ought to do is sell the dam place and move out into the country."