(FORTUNE Small Business) – A hundred years ago most of the razors, knives, and scissors in this country came from Fremont, Ohio. For most of the 20th century, companies in central West Virginia produced millions of marbles a day--virtually the entire U.S. supply. About a third of the country's demand for socks still comes from a cluster of mills in Fort Payne, Ala. And as recently as ten years ago, almost all sex-change operations in the U.S. were performed in a small town called Trinidad, Colo. Despite their varying products, these regions share something in common--all four industries are now in sharp decline.

At its peak, Fremont, Ohio, a Lake Erie town rich in natural resources, had 25 cutlery companies employing about 3,000 workers. Many were German immigrants who had brought metalworking skills with them from Europe. But declining demand for knives and scissors over the past century has put most of those companies out of business. Now just two remain, and they're scrambling to create innovative products for which price is not the main selling point. "In 1992 we moved to a niche market," says Michael Waleryszak, president of Crescent Manufacturing, which has been around since 1898 and books $12.5 million in annual sales. "With our blades, we went into food processing, textiles, and Lasik surgery."

West Virginia's marble industry has a similar history. The region's abundant natural gas and sand gave rise to an art-glass industry, whose scrap was used to make marbles. (They weren't just toys, either--glass marbles are used in everything from filtration systems to mausoleum rollers.) Now, of some nine marble manufacturers in the region, only two are still in business: Marble King in Paden City, W.Va., and Jabo in Parkersburg, W.Va. Cheap imported marbles, along with natural gas prices, which have tripled in the past five years, have impacted both companies. Last year, Jabo says, its revenues fell to $1.5 million, from $8 million in 2002, and the company posted the first loss in its 20-year history. Marble King is doing better. It cut its energy consumption by 30% and developed an exporting arm. About a third of its marbles are now shipped to eight countries overseas. Still, Marble King CEO Beri Fox, 49, is not optimistic: "How long can we remain competitive? I don't know the answer to that."

Foreign competition has also hit tiny Fort Payne, Ala., home to 75 sock mills that produce 14 million pairs a week. Unfortunately, this labor can be done more cheaply overseas, and the sock industry in Fort Payne has been getting its toes stepped on lately. The mills now employ about 5,200, down from 7,300 in 2003. The layoffs would probably be greater if the U.S. didn't set quotas on foreign sock imports. (Socks are one of the few textile and apparel products still enjoying such protection.) But those quotas will be lifted in October, and cheaper socks are likely to come into the U.S. in increasing numbers.

Trinidad, Colo., became the sex-change capital of the world thanks to one man: Dr. Stanley Biber, now 82, who performed more than 5,800 of them over a career that spanned decades. But two years ago Biber's malpractice insurance became too expensive, and he was forced to retire. A protégé (herself transgendered) is carrying on his legacy at the same hospital in Trinidad, but surgeons trained by Biber are now practicing in other cities as well, and hospitals in Thailand do a booming business in sex-change operations. To replace some of the lost revenue, the town has turned to art. A program offers gallery space to recruit artists to the area, and about 150 painters and sculptors now call Trinidad home. --HANNAH CLARK, INGRID THARASOOK, AND HALAH TOURYALAI