Ketchum was born in the 1870s gold rush, a tiny railroad town that quickly gained fame for its healing hot springs.

By the turn of the century, prospectors, ranchers and railroad workers were sharing land with well-to-do families, who were soaking in the mineral waters of Guyer Hot Springs Resort and lunching beside its croquet lawns and tennis courts.

But the equilibrium since then has been upset.

Over the past 25 years, the town near the Sun Valley ski resort has been taken over by absentee celebrities and multimillion-dollar mansions. The small-town atmosphere many believe attracted the rich and famous is in danger of disappearing as lower-, middle- and even upper-middle-income families are forced out, unable to afford homes in the most expensive housing market in Idaho.

"The people who have a sense of history here are leaving," landscaper Mike Turzian said. "It's a threat to the entire town. It's to the point now that, 75 percent of the time when I work, I never meet the homeowners."

The boom came in the 1980s and 1990s, as baby boomers came into their own. In 1990, half the people in Sun Valley and Ketchum had lived there for less than five years, according to the Census Bureau, and the trend continued over the next decade, albeit at a slower pace.

One in every four houses in Ketchum and neighboring Sun Valley is worth more than $1 million, and one in every 10 residents makes more than $200,000 a year, according to census figures.

Ask anybody on the street and they can name 15 or so famous residents.

Ernest Hemingway was one of the first. He visited Ketchum in 1939, moved here two decades later and committed suicide here in 1961.

Nowadays, Clint Eastwood, Bruce Willis and Demi Moore, Arnold Schwarzenegger and Maria Shriver are all considered fixtures. Jamie Lee Curtis has hit Sun Valley's slopes and Teresa Heinz -- the Heinz food heiress and wife of Sen. John F. Kerry (D-Mass.) -- has been an active community member for years.

Real estate agent Sherry Daech has seen the value of the "big sale" rise from $1 million to $10 million or more. Her office walls are plastered with photos of the famous and their families.

Daech, for one, does not mind the changes in her community.

"We have the most fabulous community," she said. "Years ago, we didn't even have a shoe store. Everybody left town in the spring, and all you'd see is the tumbleweed rolling down Main Street.

"Now, there are art galleries, boutiques, a great private school and a great public school," she said. "When you have more people coming into town, it brings in some of the culture of the outside world."

It can also force out a sense of community, said Pam Morris, editor of the local Idaho Mountain Express newspaper. Many of the town's workers live in Hailey, 13 miles away, or even in Twin Falls, 80 miles distant.

And the celebrities who spend time in Ketchum are elusive, Morris said.

"I can only theorize that their intent in coming here is to get away, wall themselves off," Morris said. "They live within walls in their home cities, and they live within walls while they're here."

Michel Rudigoz came to Idaho from France because of the skiing. He was the coach of the U.S. Women's Olympic Ski Team in 1980 and 1984, and owns an upscale French restaurant here called Michel's Christiania.

He credits technological advances at the ski resort for the growth in the surrounding Wood River Valley.

"The snowmaking ensured that anyone could go up any time in the winter and have a good day skiing," he said. "And the additional lifts -- instead of spending all day on the chair, now you can get all your skiing done by noon, and then come in and spend your money in town."

Brian Barsotti, a real estate attorney, said the invasion of the rich has property values -- and property taxes -- escalating at an alarming rate.

"All these people building elaborate secondary houses -- that drives the prices up, which drives the property taxes up," he said. "When your taxes go up 200 percent but your income doesn't, you have to sell. People who have lived here their whole lives are going south."

Actor Clint Eastwood owns a home in Ketchum, Idaho, a town that has been taken over by the rich and famous. Wage-earners have left.