The distance between Cedar Rapids, Iowa, and Des Moines is a little more than 100 miles. But by bus it's a 600-mile trip -- you have to go by way of Minneapolis.

With more than 50 percent of the nation's population now living within 100 miles of a coastline, the heartland of America is emptying out. And with the exodus has come a decline in intercity bus service, the public transportation lifeline stitching together thousands of rural communities.

The decision this week by strikebound Greyhound Lines to seek protection from its creditors under federal bankruptcy laws suddenly raises the possibility that the only nationwide bus company could soon be out of business. Although the company insists it will survive its current financial problems, the bankruptcy action raises serious questions about its long-term ability to stay in business.

Even if Greyhound survives, it may abandon about one-third of the communities it now serves, mostly in rural areas and the Great Plains states.

If Greyhound disappears, states such as Arkansas, Missouri, Wisconsin, Minnesota, Colorado, Montana and the Dakotas would suddenly find themselves without any intercity bus service, according to Joe Richardson, president of Russell's Official Motor Coach Guide, the transportation bible of the nation's bus industry.

Since bus service was deregulated in 1982, the pace at which communities have lost service has accelerated, according to figures compiled by the Interstate Commerce Commission. In one three-year period -- 1983 through 1985 -- approximately 3,700 communities lost service, compared with approximately 1,800 government-approved abandonments from 1972 to 1979.

While most of the population resides within metropolitan areas, approximately 40 percent of the country still lives in communities of fewer than 50,000 people, where the bus company is often the only public transportation.

Although there are many regional bus companies in operation around the country, they serve fewer than half the 10,000 communities reached by Greyhound before it was struck by its drivers in March, and few go into tiny rural areas.

"In Montana, we never thought we'd see the day when we had more buffalo than we could count and the trains were extinct," said Rep. Pat Williams (D-Mont.), the principal sponsor of a resolution in the House aimed at forcing Greyhound and its union back to the bargaining table.

Other than Williams and a handful of his congressional colleagues, however, there appears to be little concern either on Capitol Hill or within the Bush administration about the unprecedented demise of the nationwide bus system as a result of transportation deregulation. The Interstate Commerce Commission said it was actively monitoring the Greyhound situation, but a spokesman said there were no contingency plans in the event the company went out of business.

"Service to these smaller communities has just not been economical. That was the reason for the demise of Trailways and a lot of other regulated bus service," said Joseph Canny, deputy assistant secretary of transportation for policy.

Part of the reason for the lack of concern is that rural America is generally not organized in a way that draws the attention of policy makers in Washington. "The people we serve don't have a lot of clout, they aren't organized," said Greyhound spokesman George Gravely. "They are not thought of as a powerful, politically potent group like airline passengers."

What concern there has been has come, not surprisingly, from representatives in states that would stand to lose bus service.

Sen. Jay Rockefeller (D-W.Va.) said, "I'm deeply concerned about the loss of bus service that could result from the collapse of Greyhound. I have repeatedly called for more recognition of the growing problems that West Virginia and other rural areas are experiencing in access to decent transportation."

Sen. J. James Exon (D-Neb.) has introduced an amendment to the Rural Partnership Act that would establish a new federal grant program to initiate and expand intercity bus service and establish feeder services in rural areas and small communities.

David Raphael, executive director of the Community Transportation Association of America, said that even if the Greyhound strike is settled, "I think that rural America is in for a bad time." Raphael's association is a research center for transit agencies that provide rural and specialized transportation.

"It really is of an emergency nature, yet things are loping along rather casually," Raphael said. "I don't think the issues are the strike or the bankruptcy at all, but the absence of a national plan or focus on maintaining essential bus service in communities where that is the only link that people have with the outside world."

Greyhound's current troubles began when its drivers, represented by the Amalgamated Transit Union, struck the company March 2 in a dispute over a new labor contract. There have been no talks in the increasingly bitter and sometimes violent strike since"Service to these smaller communities has just not been economical." -- Joseph Canny May 18 and prospects for a settlement appear dim. Greyhound's creditors are reportedly urging the company to settle with the union, but there seems to be little interest on the part of the company to do so.

Financially, however, Greyhound was in trouble long before the strike began. Current management purchased the bus line three years ago in a highly leveraged buyout financed largely by junk bonds. Less than a year later, it took on more debt to buy Trailways, the only other nationwide bus company.

The high interest payments on loans for both the purchase of the company and hundreds of new buses have severely drained Greyhound's cash. That debt now raises serious questions about the willingness of creditors to go along with a financial reorganization, particularly in the absence of any labor agreement. The question now is whether the creditors are willing to bet on the company's future or simply get as much money as they can now by seeking liquidation of the company in bankruptcy court.

Bus companies have been struggling financially for more than a decade, losing ridership as Americans acquired more automobiles and air travel became cheap enough to compete with most other public transportation. Alfred Kahn, who led the drive to airline deregulation in the Carter administration as head of the now-defunct Civil Aeronautics Board, said that while deregulators believed there would be some competition with bus service, "I don't think anybody envisioned then competition would be so intense that buses would really be driven to the wall."

Kahn said he had opposed deregulating bus transportation. "I knew that bus service comes close to being really essential for a lot of isolated communities, for old people," Kahn said. He said the federal government should provide subsidies to communities that otherwise would be stranded.

Under federal transportation law, those nonprofit transportation providers receive a government subsidy. Even so, only about half the counties in the United States have any local public transit services, including the nonprofit operations. Four states -- New York, Michigan, Pennsylvania and Massachusetts -- provide subsidies for bus service to communities that otherwise would have no transportation.

Such subsidies would help people like George Langmack. As city administrator in Clinton, Iowa, Langmack has seen his city lose air, train and bus service over the years. Many of the people who are being abandoned by the public transportation system, he said, are "just not going to be able to see mom and dad again unless they can bum a ride or hitchhike."