NEW YORK (CNN/Money) - Rural life in the United States has undergone profound change -- more and more, country living is a pastime rather than an occupation.

Not only is the number of farms and ranches in the United States shrinking, by 20 percent over the past 20 years, to 2.1 million, but a greater slice of that smaller pie belongs to those who own farms for fun, not profit.

Hobby farms -- from which the total value of goods sold and government payments amounts to $10,000 or less -- account for some 58 percent of all U.S. farms, according to the National Agricultural Statistics Service (NASS).

Much of the land once worked by mid-sized farmers has been snapped up by vast agribusinesses. But the old farm houses remain. Many have been reborn as hobby farms, where people with non-agricultural sources of income live.

Today, 42 percent of owners work full-time outside the farm. Many of the others are retired, semi-retired, or have part-time jobs.

These nouveau-farmers may continue to grow small amounts of agricultural products, lease out their land to real farmers for planting row crops or grazing cattle, or even harvest firewood or lumber. Such practices often enable them to maintain the tax status (and lower rates) of agricultural land.

Lou Francis, president of United Country Real Estate, which specializes in selling real estate in rural areas, reports that only a handful of hundreds of sales made in the past 10 years have been for working farms. "The rest went for weekend retreats or retirement homes," he said.

The break-up of family farms has even led to statistical oddities in some locales near major metropolitan areas. For example, the number of farms is actually increasing in some areas.

NASS statistician Kevin Hintzman points out the sale of, say, a 200-acre working farm often results in the development of 20, 10-acre lots. "Half of those may qualify as 'farms,'" he says, leading to a ten-fold increase in the number of farms on that same plot of land.

Hobby farms can provide their owners many of the pleasures of farm life – beautiful vistas, clean air, peace and quiet. Nouveau farmers have room to kick around, a bit of extra income, and they can grow their own tomatoes.

Yet they face few of the tribulations real farmers do. Hailstorms, floods, drought, crop failure aren't real worries. These disasters have little real impact on income.

With family farms struggling and many urban dwellers prospering, the trend to hobby farms should only strengthen.

Farm prices look like unbelievable bargains to Manhattanites paying $800,000 for one-bedroom apartments. Combine that with the romance of country living and you have a formula for continued growth.

So when you drive down a country lane and spot a new Mercedes G500 out by the old barn, don't jump to the conclusion that the farmer made a killing in hog bellies this year. It could be some investment banker who has applied a fraction of this year's bonus to a new hobby.