Looking forward to your silver wedding anniversary?

Count yourself among a shrinking minority.

A U.S. Census Bureau study released yesterday reported that more than half of the American marriages consummated in the late 1970s failed to survive 25 years.

It was the first time since at least World War II that the Census Bureau reported that most marriages dissolved before reaching their silver anniversary.

"Twenty-five years is a good marriage now," said Lynne Z. Gold-Bikin, a prominent Philadelphia divorce lawyer for more than three decades. "In all honesty, I don't see a lot of good marriages."

The Census Bureau study, a detailed survey of about 44,000 households tracked over several years, reinforces previous studies that have reported that American marriages are not as durable as they once were.

While only 49.5 percent of men married between 1975 and 1979 celebrated their 25th anniversaries, more than 70 percent of men married between 1955 and 1959 remained married 25 years later (and 61 percent were still married 40 years after they walked down the aisle).

Experts said the findings were unsurprising - the divorce rate has remained relatively stable for the last two decades after increasing dramatically in the 1960s and 1970s.

"It's really not changing that radically," said Rose Kreider, a Census Bureau demographer who compiled the data.

The fact that more than half of all marriages now are unlikely to survive for a quarter-century is really only a milestone of modern matrimony.

"Overall, there's not a lot of change in the divorce rate," said Andrew J. Cherlin, a sociology professor at Johns Hopkins University in Baltimore. "About half of all marriages will end in divorce."

The reason for the decline in the length of marriages is no secret, experts say.

Americans are marrying later, and they have more freedom to dissolve unhappy marriages - no-fault divorce laws make the legal process easier, and they are hindered by fewer social and religious obstacles.

Modern marriages are subject to great stress, said Gold-Bikin, a partner in Wolf, Block, Schorr & Solis-Cohen. Couples now are more mobile and less likely to live near a support network of family that can help save a marriage, she said.

Americans have also become accustomed to quick fixes and have less patience to resolve complex marital problems - even some couples who have been married a long time.

"People come in my office and say they've been married for decades and want a divorce. I send them home - 'You've been married 40 years? Work it out!' "

In a recent speech to the American Academy of Matrimonial Lawyers, Gold-Bikin predicted that the serial marriages common to Hollywood might become the social norm by 2020.

Part of the problem is that many Americans, bombarded with images of lithe youth, have unrealistic expectations. She said a growing number of clients seemed eager to trade in their sagging spouses for gravity-defying trophy wives, or husbands.

"Everybody thinks they're entitled to be happy," she said.

Other highlights of the survey:

On average, first marriages that end in divorce last about eight years.

The median time between divorce and a second marriage was about 31/2 years.

In 2004, 12 percent of men and 13 percent of women had married twice. Three percent had married three or more times.

Among adults 25 and older who had ever divorced, 52 percent of men and 44 percent of women were currently married.

Just over half of currently married women in 2004 had been married for at least 15 years, and 6 percent had been married at least 50 years.