CEDAR RAPIDS, IOWA -- Here in the heartland, folks are feeling like the fellow in ''Field of Dreams.''

"If you build it, he will come," a voice urged the farmer in the movie, convincing him that a cornfield baseball diamond would bring back long-dead players.

"Build jobs, and people will come," said former Democratic congressman Mike Blouin, who now spends nearly half the year on the road as economic development director of the Cedar Rapids Area Chamber of Commerce. "People gravitate to where the jobs are. They won't move here on the hunch that there will be work. And young people are less inclined to leave if they know they can find the profession they want here. They'll stay put."

While other areas of the country struggle to institute slow-growth and no-growth policies, getting people to come and to stay is a real concern in Iowa.

In the recently released preliminary U.S. Census Bureau report, Iowa was one of a few states to show a population decline in the 1980s. According to census figures, the state's 1990 population is 2,766,658, down almost 150,000, or 5 percent, from 1980.

If those numbers hold up -- and they're being challenged all over the state -- the impact would include a smaller share of federal tax revenues and a sure loss of one of six seats in the House of Representatives.

There's also the perception of a state that's shriveling up.

So why is the second-most popular bumper sticker, behind the ubiquitous "Go Hawks" of the University of Iowa football team, another line from "Field of Dreams": "Is this heaven? No, it's Iowa"?

It's because Iowans believe that the state has already been through the worst and things are beginning to look better, although changed, as the economy adapts to the battering of its agricultural base.

Once thought recession-proof -- everybody has to eat, after all -- Iowa, like other Midwestern states, went through some wrenching times during the farm crisis of the early '80s. A lot of farmers lost their land, and some food processors and equipment manufacturers went belly up.

The mid-point in the decade was the worst, when crop and land values hit bottom. Jobs and towns dependent on the traditional agricultural economy were dealt a crushing blow. Moving vans packed up faster than you could say Corpus Christi, Tex., or Colorado Springs.

Since then, however, the state has picked itself up, although the pace and face have changed.

It's no longer Ma and Pa Kettle out on the back forty. Business now plays a key role, and the cities, rather than the cornfields, are the source of economic strength.

At the same time as the tiny northeast Iowa town of Donnan (population 7) voted itself out of existence, the Principal Financial Group was moving into its $70 million 44-story insurance headquarters in the capital of Des Moines (population 200,000). It's the tallest building between Chicago and Denver.

"Des Moines is booming," said Mike Reagan, who heads the city's Chamber of Commerce. "We're on every consultant's top 10 list as a hot spot to locate."

Quietly, Des Moines has become the third-largest insurance center in the world (behind London and Hartford, Conn.) with no fewer than 65 companies.

Sears, Roebuck & Co., Greyhound Lines Inc. and Amoco Corp. have recently opened large financial services offices in the capital city.

"There's no question we've benefited from restructuring in the state," said Reagan.

The state's second-largest city, Cedar Rapids, is also on the move. Although the census showed a slight drop in population, to 107,000, its longtime mayor won't buy those numbers.

"Look, we're at an all-time high in employment at 94,000, which is up at least 10,000 from 10 years ago," argued Mayor Don Canney. "Where are all those people living?"

Most recently, Eastman Kodak Co. announced it would build a $50 million biotechnology complex in Cedar Rapids. It will be just down the road from a new South Korean-owned brass and copper mill and a German-owned machine manufacturing plant.

"You either move forward or go backward," said Canney. "There's no status quo. And right now, this area is on a hell of a roll."

The state as a whole is not faring as well, one point of contention in the hotly contested race for governor.

Democrat Don Avenson, who is challenging eight-year Republican incumbent Terry Branstad, argues that rural areas have been ignored and that too many state giveaways have gone to companies that pay low wages.

But Branstad said Iowa is on the right track, despite charges that the state is rebounding in spite of his policies.

"For too long we were a pretty complacent ag state," he said. "Agriculture will always be important, of course, but we learned that we have to diversify.

"We lost people between 1980 and 1986, no question about that. But we've been growing and expanding ever since. We're not standing still. Looking into the 1990s, there are a lot of opportunities here."

To promote those opportunities, the state has pumped all of its lottery proceeds into economic development and has instituted tax programs to encourage new businesses. The community college system is geared up to provide extensive job training.

Add to that Iowa's reputation as the national leader in education and a work force that by some yardsticks has a 35 percent higher productivity rate than the national average.

There is evidence of a rebirth in Iowa.

Public school enrollment was up last year for the first time in two decades and increases are expected again this year. The population pendulum, after several years of out-migration, has swung the other way since 1988.

Housing starts are up and the rate of new business starts ranks second in the nation, according to state economic development director Dick Timmerman.

State economist Harvey Siegelman points out that there are nearly 160,000 more payroll jobs in the state than there were five years ago.

"That's no small change," he said. "The census numbers may be down, but that hasn't caused a panic. These patterns move slowly and are pretty predictable. It doesn't happen overnight."

Siegelman said the population shift is part of a natural course as the agricultural economy changes.

"Agriculture, as an industry, is capital intensive, so we're seeing larger farms. They're more efficient. While 100-acre farms used to be the norm, the average now is 330 acres and it's growing by 15 acres a year."

As the state loses farmers, the small towns that depended on them for customers feel the pinch.

"Little by little, these little towns are dwindling away," said farmer Bob Walke of rural Elkader in Clayton County. He said young people want jobs, "And there aren't too many $20,000 and $30,000 a year jobs around here."

Added Jim Klosterboer, a Lutheran minister in Elkader, "We export a lot of agricultural products. But we also export a lot of young people."

Siegelman said there's nothing unusual about that, either, although the rural exodus accelerated during the '80s.

"But Iowa," he said, "has always been a missionary state. We're first in the nation in test scores and our graduates are top recruitment candidates. We educate them for other states. The problem comes if they are forced to leave rather than choosing to leave."

Iowa State University sociologist Willis Goudy worries that two distinct Iowas are emerging.

"We've got some urban areas that are doing well," he said. "They've diversified, have strong economic bases and are growing. But then we have some rural areas with an aging population. It's very difficult to create new jobs in those areas."

Goudy said, however, that the state's future lies in its urban corridors.

"I'm not popular for saying it," he noted, "but the rural areas should be supportive of growth in the metro areas. It's just not going to occur in Iowa's rural areas."